The Geography of Sustainable Watershed Management: Experiences from the Department of Lempira, Honduras.
La Geografía del Manejo Sostenible de Cuencas Hidrográficas: La Experiencia del Departamento de Lempira, Honduras.
AUTHOR:
Associate Professor/Profesor Asociado
Dept. Recursos Naturales y Conservación Biológica
Escuela Agrícola Panamericana (Zamorano)
Apartado Postal 93, Tegucigalpa, Honduras
(Please note: not all figures have been included in this Internet version, they will be scanned in at a later date).
ABSTRACT
In Honduras, coverage rates for potable water supply remain relatively low, especially in rural areas. Small, disperse communities are faced with several geographical problems. The first is where to get their water from, an issue that balances proximity (the closer the watershed, the cheaper and easier to get water) with environmental health concerns (the more distant, higher-up watersheds are generally more productive and pristine). The second is that regardless of the location, most watersheds are subject to a growing range of environmental pressures related to their exploitation for firewood, lumber, agricultural production, livestock or waste disposal.
Increasingly, for financial and political reasons, the only viable mechanism for the development of rural potable water supplies is through self-help projects in which communities develop and manage their own water systems, with only partial government or NGO support. This usually involves the development of elected water committees with long-term responsibilities for management and maintenance. This raises a third geographical issue, that of the spatial information about the watershed, namely its use and how it is changing over time. These committees need to deal with an inherently geographical task, and how they can become sophisticated enough to manage the spatial questions of land-use analysis and management and resolve spatial conflicts between upstream and downstream users of their watershed is a key concern.
Rural Honduras can be classed as information poor, lacking the detailed geographical data necessary for the analysis of spatial problems and spatial change, from which good landscape management decisions can be made. Existing data is inadequate with topographic maps at 1:50,000 with 20m contours, and in many areas aerial photographs do not exist or date back to the 1970s. Water projects have been mostly planned and implemented by engineers, who have not needed or developed more detailed data. The projects are then left to be run by a community-based organization with few specialist skills or tools to conduct spatial analysis over the 20 or more years in which the potable water supply infrastructure is supposed to last. It is no surprise, therefore, that although many good engineering structures have been built, insufficient attention has been placed on the geographical element, i.e. the watershed management required to make that supply system sustainable in the face of environmental pressures that affect water quality and reliability.
Using practical experience from the Department of Lempira, this paper presents a geographer's approach to these spatial issues, one in which the limitations of data, technical and financial resources within rural Honduran communities can be overcome as a step towards achieving greater sophistication in the sustainable management of a basic natural resource - water. Teaching of simple map-making techniques to water committee members, selecting key geographical indicators measurable and mapable in the field, and using photo-histories, helps raise community awareness of watershed management priorities, and how to monitor long-term progress. This paper discusses the major elements of this approach and the advantages and disadvantages associated with its adoption.
ABSTRACTO
En Honduras, las tasas de cobertura de provisión de agua potable se mantiene relativamente baja, especialmente en áreas rurales. Las comunidades pequeñas y dispersas se enfrentan con algunos problemas geográficos. Primero es de dónde se abastecerán de agua potable? - un tema que debe balancear proximidad (mientras más cercana la cuenca, más barata y fácil de conseguir el agua) con preocupaciones de salud ambiental (las cuencas más lejanas y de mayor altura son generalmente las más productivas y prístinas). Segundo es que, sin importar la ubicación, la mayoría de las cuencas están sujetas a un rango creciente de presiones ambientales relacionadas con su explotación para leña, madera, producción agrícola, ganadería o la disposición de desechos.
Cada vez más, por razones financieras y políticas, el único mecanismo viable para realizar el abastecimiento de agua potable en zonas rurales es a través de proyectos de ayuda propia en los que las comunidades desarrollan y manejan sus propios sistemas, solamente con apoyo parcial del gobierno o las ONGs. Usualmente, esto involucra la formación de comites de agua elegidas con responsabilidades de largo plazo para el manejo y mantenimiento de los sistemas. Esto levanta el tercer asunto geográfico que es la información espacial de la cuenca, o sea su uso y como éste cambia a lo largo del tiempo. Estos comites de agua deben tratar con una tarea fundamentalmente geográfica, y cómo ellos puedan ser lo suficientemente sofisticados para manejar las cuestiones espaciales del análisis del uso del terreno y manejar y resolver conflictos espaciales entre usuarios aguas arriba y aguas abajo en la cuenca, es una preocupación crítica.
Las zonas rurales de Honduras se deben clasificar como pobres en información, sin los datos geográficos detallados necesarios para el análisis de problemas y cambios espaciales, de los que se pueden tomar buenas decisiones acerca del manejo del paisaje. Los datos existentes son inadecuados, con mapas topográficos de 1:50.000 con curvas de nivel cada 20m, y en muchas áreas las fotos aéreas no existen o son de los años '70. Frecuentemente, los proyectos de agua han sido planificados e implementados por los ingenieros, que no han necesitado o desarrollado datos más detallados. Los proyectos, entonces, quedan para ser manejados por las organizaciones de la comunidad, sin destrezas técnicas ni las herramientas para llevar a cabo análisis espaciales durante los 20 o más años que supuestamente, operará la infraestructura de agua potable. No es de extrañar que mientras que se ha construido mucha buena infraestructura, ha puesto insuficiente atención en el elemento geográfico, o sea, el manejo de cuencas necesario para hacer sostenible el sistema de abastecimiento bajo las presiones ambientales que afectan la calidad y confiabilidad del agua.
Basado en la experiencia práctica en el Departamento de Lempira, este artículo presenta una aproximación geográfica a estos temas espaciales, uno en que las limitaciones de datos, y recursos financieros y técnicos dentro de comunidades rurales hondureñas se pueden vencer como un paso hacia el logro de mayor sofisticación en el manejo sostenible de un recurso natural básico - el agua. La capacitación de comites de agua en técnicas simples de mapeo, la selección de indicadores geográficos fácilmente medibles y mapeables en el campo, y el uso de historias fotográficas, aumenta la conciencia de la comunidad acerca de las prioridades de manejo de las cuencas, y cómo se puede monitorear el progreso en el largo plazo. Este artículo discute los elementos principales de esta metodología y las ventajas y desventajas asociadas con su adopción.
I. HONDURAS AND ITS WATER SUPPLY SITUATION
Where we stand in the water supply sector in Latin America and Honduras.
In Latin America and the Caribbean, 1990 data indicates that there are still 54m people without potable water service. The estimated cost in 1990 dollars to provide coverage through simple communal systems would be around $1,962m (PAHO, 1990).
Coverage rates in Honduras for water supply remain relatively low, at around 65% of the total population. While over the duration of the International Drinking Water Supply and Sanitation Decade (1981-1990), conditions improved in relative terms, absolutely, because of the increasing population, the number of people without access to adequate drinking water supplies actually increased.
According to census data, between 1974 and 1988, Honduras' population grew on average by 3.7%. This meant that while rural water coverage increased from 22.2% to 45.1% between 1974 and 1988, the total rural population still unserved with potable water in 1998 was 1.48m compared to 1.44m in 1974 (PAHO, 1990).
Lempira Department is estimated to be one of the least served areas of Honduras with adequate access to potable water of only 36.4% in 1988 according to census data. With an estimated unserved population of 112,554, coverage would need to increase by an annual average of 8.8% between 1991 and 2000 to meet goals of universal coverage, well above the average of 6.9% expansion of coverage per annum needed for Honduras as a whole.
Further expansion of water supply systems towards universal coverage will be an expensive and difficult goal.
At the end of the International Drinking Water Supply and Sanitation Decade, many countries adopted the goal of universal water supply and sanitation coverage by the year 2000 as their next goal, seeking to mobilize donor support for much of the capital costs associated with this basic social policy. On the assumption that universal coverage could be achieved during this decade, it was estimated that for Honduras alone, the total costs of meeting rural water needs, depending on the type of water systems developed, would be between $117m and $176m in 1990 dollars.
It is likely that these dollar estimates are on the low side because the majority of gains in water supply coverage over the last twenty years have taken advantage of the more easily reached communities and easily exploited sources of water. Consequently, unit costs have been relatively low, compared with what they will be in the future, and the expansion of coverage has been relatively rapid. Both of these characteristics can be expected to make a change for the worse for the following reasons:
Wise infrastructure investments and sustainability in the water supply sector are more than ever the objective.
In the context previously described, future projects for the development of potable water supply will need to take into account certain basic issues:
Increasingly, the most viable mechanism for the development of rural potable water supplies is through self-help projects in which communities develop and manage their own water systems, with only partial government or NGO support. This usually involves the development of elected water committees with long-term responsibilities for the management and maintenance of the water supply technology developed to maintain daily quality and quantity at levels sufficiently high to guarantee public health.
II. THE IMPORTANCE OF WATERSHEDS FOR GRAVITY FED WATER SUPPLY SYSTEMS IN RURAL HONDURAS
The water system of choice in rural Honduras is the gravity fed piped water supply from upland water sources.
The water supply technology of choice in rural Honduras, because of its relatively lower cost, simplicity of construction and generally higher water quality delivered has been the gravity fed piped water supplies from surface sources. Like in many other hilly or mountainous areas in the dry and humid tropics, most rural populations receive their water from gravity fed stand-pipes or "pila" house connections from upland springs or, in some cases, surface streams. An important element of the long-term sustainability of the water systems developed, and yet to be developed, is the ability of the communities for whom and with whom the systems are constructed, to carry out not only the long-term maintenance of the engineered systems (valves, pipes, tanks, intakes, chlorination systems, etc.) that bring water to beneficiaries, but also in the management of the watershed areas in which this water supply is generated.
How watershed management, a relatively specialized and sophisticated set of land management policies and practices, can be developed and applied effectively by a relatively new and largely voluntary set of community institutions, with few financial resources and starting largely from scratch, is a key concern right now in many development circles.
Watershed Management - Running to catch up in the face of rapid environmental change.
Watershed management components have not been included in most completed projects to develop water supply systems. In the development of their systems, small, disperse rural communities or their benefactor agencies inherently consider watershed conditions in their decision as to where to get their water from, an issue that balances proximity (the closer the watershed, the cheaper and easier to get water) with environmental health concerns (the more distant, higher-up watersheds are generally more productive and pristine). But more often than not, the consideration has stopped there.
In many cases in Honduras, rural development projects have selected the more distant and higher up watersheds as their preferred water sources, accepting greater per unit capital costs for the development of the water supply system in order to assure cleaner, higher volume and more regular water supplies than those they could achieve from the more deforested, highly settled, lower and closer watersheds. However, this by definition has created a physical and perceptual dislocation between the community building and benefiting from the water supply and the area in which this water supply is produced. In many cases, this problem of "out of sight, out of mind" has created a situation in which the catchment has been left untended.
Unfortunately, projects have in the past not taken advantage of the presence of volunteer workers and their families from distant beneficiary communities engaged in system construction to conduct an on-site program of education as to the nature of the catchment area and its importance to them. Projects have not mapped or established comparative baseline data on those watersheds which could be used as a basis for monitoring change, for planning or prioritizing land management measures that should be undertaken within them to guarantee continued reliability of the quality and quantity of water produced, nor mobilized people to carry these measures out as an integral part of the project cycle.
Watersheds are changing for the worst and fast.
The omission of on-site activities of mapping and management at the time of exploiting each watershed has proven an important one. In most Honduran locations today, the majority of watersheds are subject to a growing range of environmental pressures related to their exploitation for firewood, lumber, agricultural production, livestock or waste disposal. What started out as a relatively pristine watershed may quickly become the next zone of resource exploitation and agricultural expansion, with associated patterns of deforestation, burning, habitation by people and cattle and increased use of chemicals. What may have been a watershed of relatively limited or episodic use, may become one of more intensified permanent production as roads are upgraded and population pressures grow.
In the south of Lempira Department, Honduras, for example, 79% of the landscape is reported as being deforested and considerable pressure is being exerted on the remaining forested areas by traditional milpa farmers, vegetable producers, cattle owners and small-scale timber and firewood extraction. The forests contain mixed broadleaf and coniferous species and are concentrated in the higher altitude watersheds at the top of the mountain ranges. It is these higher altitude watersheds that have been used as preferred water sources in the majority of the water infrastructure projects developed in the region. One example: the watersheds of Congolón where sources are located at around 1900 m above sea level and provide water supplies to over 30 communities, some more than 50 km away.
Because of patterns of land title typical for Honduras in which much of these water sources are generated from and located on public or communal lands, few Lempira water sources come with watersheds that are owned or administered by the beneficiary communities or over which control of land use practices or upstream water use can be exerted by legislative means. Many watersheds are actually occupied by a tapestry of de facto land entitlement in which families, often living in distant villages, have historical use rights over broad areas. Thus development projects like those carried out in Lempira have invested considerable resources in the construction of extensive water projects within a region without securing control over the long-term future of the area on which they depend for the quality and sustainability of the water they need. In many cases, the sustainability of systems has been placed at a serious disadvantage by the failure to raise community awareness as to the value of land management upstream of their water system intakes at the time the communities participated in their construction. In most cases, original conditions in the watershed at the time of construction are not known because maps were not prepared, and adequate, objective environmental data were not gathered.
III. RETOOLING WATER DEVELOPMENT PROJECTS TO INCLUDE A SUSTAINABLE WATERSHED MANAGEMENT PERSPECTIVE
Water Committees are taking the lead in the integrated planning of water systems.
It is in this context that watershed management has begun to receive more equal attention alongside engineering efforts. In Honduras, this is nowhere more true than in the southern part of Lempira (Figure 1) where the major protagonist in promoting rural water infrastructure development through gravity fed piped supplies over the last ten years has not been the national government but a local non-governmental organization, COCEPRADIL, aided by its international counterpart, Catholic Relief Services.
Through an enlightened approach to the continual and integral nature of successful resource management, it is they that are taking the lead in this new move to safeguard future water supplies through inclusion of integrated watershed management into water development projects. In new projects, watershed management is now being treated as a preparatory element of project planning and source selection and development; in projects already completed, attempts are being made to develop retroactive programs for those systems' watersheds.
COCEPRADIL, or the Comité Central Pro-Agua y el Desarrollo Integral de Lempira, is a tightly-knit confederation of regional water committees formed from and committed to serving more than 80 beneficiary communities (and growing) in the areas of potable water supply development and management, rural sanitation, agricultural improvement, adult literacy, and other key areas. It is based in Candelaria, Lempira (Figure 2) with satellite offices in several other towns. It is constructing a regional training center and administration building in Candelaria to promote its capacity building activities in these key areas. It recently received confirmation of a large supporting grant from the Honduran NGO development project clearing house, Fundación VIDA, designed to complement the support received from Catholic Relief Services (CRS), in furthering its aims in the region.
The number of regional committees and their individual community members associated with COCEPRADIL is growing as CRS and now Fundación VIDA assisted potable water projects expand throughout southern Lempira Department. They have developed, to date, 42 individual watershed spring and stream capping systems using gravity-fed rural aqueducts constructed with financial and technical aid from CRS, along with self-help contributions of labor and materials, and continuing maintenance and management by the beneficiary communities, overseen by COCEPRADIL and the affiliate regional committees.
Information gathering is the first step in effective watershed management.
According to FAO (1992), watershed degradation is defined as the loss in value over time of the productive potential of water and land, accompanied by pronounced changes in the hydrological response of the fluvial system as represented by worsening quality, quantity and regularity of source flows. In Honduras, this manifests itself as reduced critical dry season daily flows, the limiting factor for supply systems in which usually no more than one day of emergency storage capacity is built.
Also according to FAO, the management of watersheds is a process of formulating and implementing a systematic action plan that includes the management of the resources it contains to obtain goods and services on a sustained basis. Watershed management is thus a continual process that requires a steady and quality supply of spatial information about the land and resources it contains, namely their use and how it is changing over time, linked to knowledge of how the hydrological system is reacting or could react as a consequence in the future.
COCEPRADIL, as befitting a campesino organization developed largely from scratch to promote community-based projects in a historically marginalised region of Honduras, has relatively little or no experience in systematic watershed management or monitoring. They have thus recognized that they need help in developing the necessary sophistication as an institution to develop and manage the kinds of spatial questions of land-use analysis and management and to resolve spatial conflicts between upstream and downstream users of the watersheds on which they rely for their continuing potable water supplies.
In 1993, the Escuela Agrícola Panamericana, more commonly known as Zamorano, began an informal association with the water committees represented by COCEPRADIL, and their international counterpart and support agency, Catholic Relief Services, to help develop a strategy for watershed management within the project area. The first stage was for Zamorano to assist in a baseline study in which a mapping exercise was conducted for seven of COCEPRADIL's watersheds financed by CRS. Rather than have Zamorano or any other outside agency carrying out this mapping, it was decided that the better strategy would be to empower COCEPRADIL to plan and develop its own databases. This subsequently evolved into a project to help COCEPRADIL independently take on board some of the more practical concepts of integrated sustainable watershed management and techniques for the generation of spatial data on watershed characteristics and change, to aid them in their long-term goal of the sustainable and integrated development of their region. As part of this process, several members of COCEPRADIL participated in an international short-course on watershed management at Zamorano in May 1995 (Lee, 1995). The principal vehicle for this capacity building was the Zamorano-led research into developing indicators of sustainable development which is being carried out in Honduras as part of the global collaborative research support program known as SANREM (Sustainable Agriculture and Natural Resources Management) financed by USAID. Together, COCEPRADIL's Micro Watershed Project and Zamorano began to develop local institutional potential to quantify and monitor watersheds. The idea is to train project staff to develop and maintain community databases on watersheds designed to answer important spatial questions like what are the physical characteristics of each watershed, what are its environmental problems and how are they changing. These are all necessary first steps in the process towards developing environmental solutions and preventing long-term negative impacts on water supply productivity and quality due to watershed use.
IV. THE GEOGRAPHICAL ASPECTS OF SUSTAINABLE WATERSHED MANAGEMENT
Getting to grips with watershed management requires good geographical knowledge.
Watershed management, requiring as it does the management of the land and its resources over time, is first and foremost a geographical task requiring information that in some way must be mapped and monitored. Borrowing from the jargon of the 1990s, what is needed by the institution responsible for carrying out the long-term management of a watershed over the 20 or more years in which the potable water supply infrastructure they have built and must maintain will last, is some form of geographical information system. This geographical information system must establish baseline, and preferably historical, conditions, must be sensitive to change and must be continually updated to show the change, positive or negative, in response to any management activity or inactivity on the part of that institution. This information must be used to communicate and make informed management decisions and guide the efficient and effective use of the limited resources available for that management. The degree of formality of the geographical information system is in large part a function of the sophistication of the institution and the resources available to it, but at a minimum can be considered an ordered physical archive of data with a combination of maps, diagrams and tabulated data updated over time.
Developing a watershed geographical information system with few resources is a field-intensive process.
In contemplating this process in Lempira, certain fundamental obstacles were encountered. Rural Honduras can be classed as information poor, lacking the detailed geographical data necessary for the analysis of spatial problems and spatial change, from which good landscape management decisions can be made. A basic problem typical in Lempira and many other rural parts of Central America is the lack of access to suitable secondary data sources adequate for watershed management at the small to very small catchment scale. These watersheds, from less than 1 km2 to around 4 km2 in area, are the predominant types of upland, first-order catchments preferred and used as sources of potable water for remote, beneficiary communities downslope.
It was concluded that for this type of watershed, a simple field surveying technique must painstakingly be applied for the mapping of watershed boundaries, hydrological systems and land-use zones. Topographic base maps seldom exist at a scale larger than 1:50,000, with contour intervals of 20 m or more. Even when photocopied and enlarged to a scale of 1:5,000, for example, they do not provide any more information and as a mapping tool are extremely limited because they cannot show the actual complexity of drainage networks, slope orientations and the exact location of drainage divides.
Aerial photographs are usually not available and are costly to have taken, particularly when the region is remote and the individual watersheds are dispersed, as in the case of COCEPRADIL where the 42 watersheds already developed are distributed within the 1,000 km2 southern half of a complete department of Honduras. Moreover, the equipment or financial resources necessary to produce maps through photogrammetry are not found within the community organizations.
With outside help, new technologies such as Global Positioning Systems (GPS) are sometimes available (as in the case of Honduras where Zamorano has a Trimble Pathfinder system which could be used in base mapping), but present problems related to the lack of electricity supply within the community for the charging of batteries and the periodic downloading of rover unit databases for incorporation with base-station data. Also, since many of the watersheds are steep and forested in parts, GPS systems frequently cannot locate sufficient satellites to generate accurate coordinate data. Even assuming an outside agency such as Zamorano could carry out the data processing and map production, it must be carried out away from the community and updating and expansion of information bases subsequently is not within the capability of the community themselves.
Field mapping of a watershed is an opportunity to learn about the water system.
Based on these considerations, the only sustainable technique available at the community level that is rapid enough to be applied to baseline data development and updating is the compass-Clinometer-tape measure surveying technique that applies triangulation and/or transect line principles to map important line and point geographic features within the watershed. The belief is that while being a significant chore for those involved, nevertheless the mapping is itself a positive process. This is because spending time in the watershed, thinking about how to map it, and then carrying out data collection focuses community members on the complex nature and interactions within and outside the watershed boundaries that will determine the quality and quantity of water produced, as well as the quality of life of those living there.
To this end, Zamorano and COCEPRADIL have been honing the techniques for preparing these spatial databases by conducting a series of workshops with a range of participants typical of the cross-section of community members who would be charged with carrying out watershed management and data gathering of baseline conditions and patterns of change. The participants bring with them highly varying educational backgrounds from a three-year college training in agronomy to a basic third-grade primary school education. Experience has shown that they can relatively easily be taught in a highly practical fashion the necessary skills to map a watershed with only basic field equipment.
V. PUTTING TOGETHER A COMMUNITY-BASED GEOGRAPHICAL INFORMATION SYSTEM
The following section presents a brief description of the elements of the mapping methodology adopted in the work by Zamorano and COCEPRADIL. As part of the SANREM CRSP research project, a full accounting of the methodology and its results will be presented later this year as a manual developed from and geared to the specific needs of the COCEPRADIL field workers and members, along with a second document of exercises and instructions for the training of field mapping teams.
Watershed mapping is a systematic methodology that stresses landscape interpretation.
The methodology includes the following steps:
1. Field reconnaissance and group discussions in the field concerning the process of mapping, which elements of the watershed to be mapped and why, and the observable characteristics and evidence of change within its boundaries.
2. Preparation of a sketch map of the watershed from high altitude points along the watershed divide, with the individual geographical elements to be mapped identified along with their common points (control points).
3. Preparation of an inventory of elements to be mapped, an estimation of the time required for mapping, and a timetable and sequence of mapping.
4. Preparation of an inventory of control points to be marked in the field for later reference (for example a point of return for starting another element on a later day of mapping), and selection of a method of marking (colored tape, paint, marker posts, etc.)
5. A full day or preferably half-day, depending on logistics, of mapping, followed by a full day or half-day of data analysis and drawing of map in the field. In most cases, calculations and drawing will be done by hand, but on rare occasions when a computer is available (they are not in the Lempira project), it can easily be done in a program like Lotus 1-2-3 using the spreadsheets developed by the author.
6. Repeat of step five until all the mapping elements have been incorporated.
7. Workshop to discuss the map, its contents and its significance for management purposes, if necessary with another visit to the watershed to confirm impressions and/or share the outcomes with those living in or benefiting from water produced from the watershed.
Table 1: Watershed divide data collected by field mapping (see figure 3)
From |
To |
Compass |
Slope |
Distance |
Height Change |
Horizontal Distance |
Map Distance |
X |
Y |
Spot Height |
deg |
deg |
m |
m |
m |
cm |
cm |
cm |
m | ||
0 |
1 |
349 |
15 |
5.40 |
1.40 |
5.22 |
0.5 |
-0.1 |
0.5 |
1.4 |
1 |
2 |
335 |
25 |
8.93 |
3.77 |
8.09 |
0.8 |
-0.4 |
1.2 |
5.2 |
2 |
3 |
322 |
40 |
10.25 |
6.59 |
7.85 |
0.8 |
-0.9 |
1.9 |
11.8 |
3 |
4 |
329 |
31 |
7.00 |
3.61 |
6.00 |
0.6 |
-1.2 |
2.4 |
15.4 |
4 |
5 |
342 |
24 |
48.17 |
19.59 |
44.01 |
4.4 |
-2.6 |
6.6 |
35.0 |
5 |
6 |
355 |
41 |
17.70 |
11.61 |
13.36 |
1.3 |
-2.7 |
7.9 |
46.6 |
6 |
7 |
11 |
32 |
14.92 |
7.91 |
12.65 |
1.3 |
-2.5 |
9.1 |
54.5 |
7 |
8 |
354 |
32 |
19.70 |
10.44 |
16.71 |
1.7 |
-2.6 |
10.8 |
64.9 |
8 |
9 |
333 |
26 |
19.53 |
8.56 |
17.55 |
1.8 |
-3.4 |
12.4 |
73.5 |
9 |
10 |
325 |
11 |
31.25 |
5.96 |
30.68 |
3.1 |
-5.2 |
14.9 |
79.4 |
10 |
11 |
302 |
14 |
58.80 |
14.23 |
57.05 |
5.7 |
-10.0 |
17.9 |
93.7 |
11 |
12 |
289 |
29 |
34.02 |
16.49 |
29.75 |
3.0 |
-12.9 |
18.9 |
110.2 |
12 |
13 |
307 |
13 |
19.95 |
4.49 |
19.44 |
1.9 |
-14.4 |
20.0 |
114.6 |
13 |
14 |
275 |
16 |
40.52 |
11.17 |
38.95 |
3.9 |
-18.3 |
20.4 |
125.8 |
14 |
15 |
289 |
17 |
26.90 |
7.86 |
25.72 |
2.6 |
-20.7 |
21.2 |
133.7 |
15 |
16 |
287 |
21 |
47.92 |
17.17 |
44.74 |
4.5 |
-25.0 |
22.5 |
150.9 |
16 |
17 |
302 |
7 |
19.74 |
2.41 |
19.59 |
2.0 |
-26.7 |
23.6 |
153.3 |
17 |
18 |
319 |
9 |
28.34 |
4.43 |
27.99 |
2.8 |
-28.5 |
25.7 |
157.7 |
18 |
19 |
317 |
11 |
43.43 |
8.29 |
42.63 |
4.3 |
-31.4 |
28.8 |
166.0 |
19 |
20 |
319 |
11 |
47.65 |
9.09 |
46.77 |
4.7 |
-34.5 |
32.3 |
175.1 |
20 |
21 |
303 |
8 |
37.90 |
5.27 |
37.53 |
3.8 |
-37.6 |
34.4 |
180.3 |
21 |
22 |
217 |
16 |
22.53 |
6.21 |
21.66 |
2.2 |
-38.9 |
32.6 |
186.6 |
22 |
23 |
280 |
11 |
40.97 |
7.82 |
40.22 |
4.0 |
-42.9 |
33.3 |
194.4 |
23 |
24 |
257 |
29 |
40.07 |
19.43 |
35.05 |
3.5 |
-46.3 |
32.5 |
213.8 |
24 |
25 |
269 |
12 |
26.34 |
5.48 |
25.76 |
2.6 |
-48.9 |
32.5 |
219.3 |
25 |
26 |
304 |
14 |
33.89 |
8.20 |
32.88 |
3.3 |
-51.6 |
34.3 |
227.5 |
26 |
27 |
333 |
8 |
59.20 |
8.24 |
58.62 |
5.9 |
-54.3 |
39.6 |
235.7 |
27 |
28 |
293 |
6 |
57.33 |
5.99 |
57.02 |
5.7 |
-59.5 |
41.8 |
241.7 |
Map preparation is a hands-on process.
Table 1 presents an example of the types of data produced as part of a field mapping process. This data, which represents one half of the divide of a watershed, was mapped by two separate field teams made up of seven representatives of COCEPRADIL and its member communities, ranging from rural educators to campesino farmers, at one of the training workshops conducted in a small, steep watershed close to the Zamorano campus and similar to those encountered in Lempira. Generally, raw data from the field is hand calculated on solar calculators that must have the trigonometric function keys of sine and cosine. Appropriate formulae to calculate and scale heights and distances for plotting are taught to the field data collectors as part of the process. Maps are plotted by hand on millimetric graph paper using a protractor, ruler and pencil. Generally, the time required for data calculation and map preparation is exactly equal to the time spent in the field obtaining the raw data.
In Table 1, the formulae used by field collectors has been programmed into a computer spreadsheet along with additional formulae that permit the Cartesian coordinate of each field point to be determined, assuming the principal control point (usually the outlet of the watershed) is (0,0,0). Thus, it is actually not necessary to calculate and draw the point, line or polygon elements by hand with a protractor and ruler but instead only plot and connect together each point. This has been done automatically using the graphical routines of the computer spreadsheet (Figure 3). The result is exactly the same as doing so by hand, except that it eliminates user drawing error. However, in Lempira, COCEPRADIL does not possess the necessary computer hardware, expertise or access to electricity nor are likely to do so in the foreseeable future; therefore only the manual method is taught to field workers.
Figure 3: Watershed divide mapped from field data (with errors corrected)
GIS principles can be communicated in practical terms.
In this approach, Zamorano researchers have purposefully adopted the language and concepts of GIS in that watershed elements to be mapped are functionally divided into points, lines and polygons and the relationships between them considered prior to any data collection. From a geographer’s perspective, the procedures by which the community maps out a watershed represent a form of field digitization process. The mappers must decide on a template for the watershed, and a series of layers for their mapping, represented by separate sessions in the field, in which a logical and systematic order is determined for the mapping of elements designed to save time and minimize error, while accounting for the essential connectivity or topology within the watershed. The fieldworkers can learn relatively easily and quickly to start and finish one layer of the map before going on to another and at the end of the process, they are integrated and errors checked by way of their common elements. Each element is selected and considered as to its importance and its relation to each other element. No element is included that does not have practical significance for understanding the watershed and its dynamics.
Table 2: Typical Geographical Elements in a Watershed Map
| Element | Examples |
| Polygons | Watershed divide. Plots of land. Areas of different land-use within the watershed. |
| Lines | Streams. Roads. Limits of different land-use that extends beyond the watershed. Water pipelines. Paths. Fences or walls. |
| Points | Houses. Key water features: wells, standpipes, spring upwellings, tanks, junction boxes, intakes, stream branching points, etc. (some may already be points marked on line elements). Latrines. Water troughs. Laundry/bathing points. |
From the mapping perspective, the following elements generally must be mapped for each watershed:
1. Polygons
They must have a minimum of one control point and must begin and end at exactly the same marked point in the watershed, e.g. a tree, a post, or other recognizable point (that should be made more recognizable by the use of marker tape, paint, or some other such indicator).
2. Lines
They must begin at one control point, i.e. a known, marked mapping point along another element, if possible the watershed divide. They must end at another control point.
3. Points
They must be mapped by connecting them with transect lines to tie them in with one or more control point.
Control Points
The following are excellent control points in the watershed because of their relative ease of identification:
The watershed map is a tool for understanding the water system.
The geographical information system or watershed map can be used to understand where risks lie in terms of the quality, quantity and reliability of water produced from the watershed. An idealized illustration of the typical kind of watershed map produced is provided in Figure 4, which shows the spatial relation between different elements within the polygon represented by the watershed divide. Each point, line and polygon is mapped in the field using a Clinometer, compass and tape measure. Since the data collector is careful to exploit the connectivity or topology of the elements by beginning and ending each element relative to other control points, they can all be drawn on the same coordinate system following careful trigonometric calculations.
Through field mapping it is possible to quantify the:
These data, amongst others, can be used as a source or basis to determine the relative perils and sensitivities within a given watershed and the need for management. Comparison of conditions in different watersheds using systematic criteria derived from the different maps, for example, the percentage of deforested land, can provide a basis for prioritizing management efforts where human and financial resources are limited.
Development of appropriate standard field indicators to be tied into watershed base maps and the periodic monitoring of change from which COCEPRADIL can make and monitor its management decisions will be the next phase in this research work. One element of this method will be the use of photo-histories of the watershed established from permanent key points of reference in the geographic information system. These histories can provide independent, objective impressions of change and form part of the institutional memory of COCEPRADIL, an independent view over the lifetime of the watershed and water system regardless of the personnel involved. The assumption is that a pictorial record provided by photographs, taken from the same location, at the same angle and inclination, at the same time of year, using the same type of film and camera, is not influenced by the types of subjective judgements and misrepresentations that written descriptions or sketches might produce. Moreover, photographs are transportable and usable as part of awareness raising in so much that it becomes difficult to ignore evidence of change. For example, promotion of reforestation programs could be aided by pictorial evidence of forest degradation, the impacts of fire, or the encroachment of pasture lands on areas important for water system recharge or the capture of occult precipitation. Photographs are a very visually powerful, and relatively low-cost and feasible method of illustrating the characteristics and changes of those elements mapped as part of the baseline surveys of watersheds.
VI. CHARACTERISTICS OF THE APPROACH TO WATERSHED MAPPING AND MANAGEMENT
The current approach was developed based on a consideration of several aspects:
The techniques developed and being applied as part of institution building in Lempira have their advantages and disadvantages.
Advantages include simplicity and the chance to get to know the subject.
A principal advantage of the mapping system is that it requires instrumentation no more sophisticated than a Clinometer, sighting compass, 60m tape measure and solar calculator with limited scientific functions. These are available for a total of less than $400 and their use, based on experience from Lempira, can relatively easily be understood and mastered by campesino farmers with a 3rd grade education. From the point-of-view of local NGOs with limited financial resources, the equipment is usually obtainable since it represents the kind of small-scale capital purchase that partner institutions are often prepared to provide.
With prior training and the provision of appropriate educational materials, the simple trigonometric calculations required to process the field data and the scaling and hand drawing of maps are also relatively easy to grasp, according to experience from workshops with COCEPRADIL.
A second advantage stressed, by those who have partaken in a number of mapping exercises in different watersheds, is that the seven steps listed above require that one gets to know one's subject in the most physical of terms. The process of being a human digitizer, disassembling the watershed into its principal elements and mapping each point, line and polygon with one's eyes and feet leads to a greater understanding of size, spatial arrangement and spatial interaction between elements. The process of fixing each element in its geographical context leads to intensive debate concerning the nature of environmental problems associated with the good or bad juxtaposition of water systems, agricultural systems and other types of land uses. It provides a basis for the development of indicators of risk and change, for example, the movement of boundaries such as a forest line or the proximity of negative elements such as pollution sources relative to critical control points such as water intakes. When those undertaking the mapping are the direct beneficiaries (or their appointed representatives) of the water produced by those watersheds, as in the case of COCEPRADIL, the effect is to empower them towards the process of rationalizing and implementing the steps needed to manage those aspects of the watershed in conflict with its function as a water source.
Disadvantages include the time required, field logistics and opportunities for human error.
A principal disadvantage is the amount of time needed to conduct the mapping and data analysis process, which commits four to six people for a whole week to the mapping of a watershed of 1-2 km2. Clearly, this requires that the watershed mapping process be prioritized. For example, in the case of COCEPRADIL, it already has over 42 watersheds developed as water supplies for its member communities, none of which have been mapped in a quantitative manner. However, since there is no alternative to field mapping in many rural contexts such as Lempira, this disadvantage is moot.
A second disadvantage is the logistics associated with mapping watersheds which are steep, often precipitously so, forested with very dense understories of tall grasses and spiny shrubs, and subject to rainy or misty weather conditions for several months of the year. This combination of logistical factors generally precludes efficient mapping for half of the year, with an intensive mapping season in the dry months or early rainy season when field mappers can more easily traverse the hillsides as well as get a good feel for land-use conditions, including the use of fire in vegetation clearance.
A third disadvantage is the opportunities for human errors of a compound nature throughout the collection and processing of the data. Opportunities for mistakes include (in order):
Since the map preparation requires the drawing of each line segment defined by a set of Clinometer, compass and tape measurements, starting at point (0,0), then continuing from the end of each segment to each next segment, the errors can be compounded as much as they can cancel each other out. Regardless, a certain amount of error is unavoidable and is uncontrollable unless it is a correctable physical mistake (wrong transcription or formula) which could be found by rechecking transcripts or by recalculating. However, it is possible to calculate the total combined error with polygon features, for example the watershed divide, since if the polygon begins at (0,0) it should also end at (0,0). If the polygon is mapped as two separate halves starting and meeting at the same points, the end points should meet at the same (x, y). The size of the error can be measured in the horizontal (east-west) and in the vertical (north-south) on the hard-copy millimetric graph paper or calculated in the computer spreadsheet. Assuming that the error was caused incrementally over the whole element, each point can be modified by a small proportion of the error to bring the ends of the polygon into line. This procedure too can relatively easily be learned by data collectors. Experience from workshops with COCEPRADIL has shown that errors can be minimized by good training and by mutual, internal cross-checking and supervision by data collectors in the field and during data processing.
ABOUT THE AUTHOR
Michael D. Lee is a British Geographer currently working as Associate Professor in the Department of Natural Resources and Conservation Biology at Zamorano, the Pan-American School of Agriculture, Honduras. He is responsible for watershed management and water resources teaching and research within the Agronomy and Agronomic Engineering programs. He is also coordinator and principal investigator of the Honduran site program of the USAID-funded SANREM CRSP (Sustainable Agriculture and Natural Resources Management Collaborative Research Support Program) under whose aegis the applied research work for this paper was carried out. He holds a bachelor's degree in geography from the University of Nottingham and a doctorate in geography from the London School of Economics and Political Science. He has lived and worked in Honduras for the last three years and is a permanent resident of the United States.
ACKNOWLEDGEMENTS
The author wishes to acknowledge the contribution of Ing. Nelson Villatoro who assisted in the fieldwork and workshops carried out as part of this applied research. He also wishes to thank COCEPRADIL and its members, particularly Manuel Bonilla and Jose Ramírez, for their collaboration and assistance in developing and applying this methodology, and the helpful assistance and support provided by Catholic Relief Services of Honduras. The financial support for this work was provided by SANREM CRSP, coordinated by Dr. William Hargrove at the University of Georgia.
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Lee M.D. (1995). "Curso Internacional de Manejo Integrado Sostenible de Cuencas Hidrográficas". Text for short course given at the Escuela Agrícola Panamericana, Honduras, May 29-June 3, 1995. 95 pages plus annexes, diagrams, maps and aerial photographs.
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