Watershed Management Compendium

Teaser:

This compendium by Dr Mihir Kumar Maitra answers all questions that will be of great use to practitioners engaged in both engineering and management aspects of watershed management in the field.

Watershed management in India (Image Source: India Water Portal)

This compendium by Mihir Kumar Maitra is a valuable resource for all practitioners engaged in watershed management activities in the field. The first part of the book addresses the technical and engineering aspects useful in developing natural resources like land, surface water, groundwater, crops and forest while the second part discusses aspects related to formulation, appraisal and implementation of watershed projects by involving the beneficiaries in the process.

Please view some of the important questions that the book addresses in the context of watershed development below:

What is a watershed?

A watershed is defined as a topographically delineated geographical area in which the entire run off tends to converge through the existing drainage system to the common outlet of the area for subsequent disposal. One watershed is separated from another by a natural boundary known as the water divide or the ridge line. In short, a watershed is an independent drainage unit for surface water runoff.

What is watershed management?

Watershed management is the process of formulating and carrying out a course of action involving the manipulation of natural, agricultural and human resources in a watershed to provide goods and services that are desired by and suitable to society, under the condition that soil and water resources are not adversely affected. Watershed management must consider the social, economic and institutional factors operating within and outside the watershed (FAO, 1987).

What activities are undertaken in integrated watershed development projects?

The common physical components in a watershed development project or programme are:

Soil and water conservation
Plantation
Agronomical practices
Livestock management
Renewable energy
Institutional developments

A number of activities under integrated watershed development projects mobilise community participation to create sustainable outcomes. These involve:

Establishment of rapport through entry programme(s);
Creation of awareness about the project objectives;
Preparation of village level implementation plans in consultation with the community;
Formation of user groups and project management committees;
Development of capacities within the user groups and management committees;
Implementation of project components through user groups and project management committees;
Mobilization of community contribution;
Conflict resolution and follow up.

What is the hydrological cycle?

Hydrology is the science that deals with the occurrence, distribution and movement of water within the earth and its atmosphere. The hydrological cycle is a dynamic water transfer system of nature, wherein the water is continuously moving and changing from one form to another, while its sum total remains the same.

The hydrological cycle determines the amount of water available and the movement of water in the watershed.

After reaching the earth’s surface, rainfall (or snow) continues to move and change its form. The part that enters the soil is infiltration; the part which flows along the surface is run-off; the part which goes back to the atmosphere as water vapour is evaporation and the part that is transpired by the plants back to the atmosphere is transpiration. Further, the part which is intercepted by leaves and stems of existing vegetative cover is interception, the part which is collected on the surface is surface storage, the part which is retained in the soil is soil moisture and the part which percolates below the soil zone to join the saturated zone is groundwater.

Thus, the static water balance equation in its simplest form, may be written as: Precipitation = Run off + Evapo-transpiration + Change in Storage

How is subsurface water distributed in a watershed?

Water occurring in subsurface formations can broadly be divided into two horizontal segments. The upper horizon is the zone of aeration and the lower segment is the zone of saturation. The zone of aeration remains filled partly with air and partly with water. The water occurring in this zone is known as soil water. In the zone of saturation, all the pores remain saturated with water. Water occurring in this zone of saturation is known as groundwater. The upper surface of the zone of saturation is the water table.

A third zone - the unsaturated zone, often exists between the zone of aeration and the zone of saturation, particularly when the water table is deep. This intermediate unsaturated zone however, gets saturated temporarily during the monsoon, when groundwater is recharged from rainfall. The zone of saturation containing groundwater, on the other hand, extends downwards till the bedrock in hard rock areas or till an impervious clay layer is encountered in alluvial areas. More such saturated zones may occur underneath the first one in case of multi-aquifer systems common to thick alluvial deposits.

Water occurring in the pores and interstices of sub-surface formations, to its level of saturation, is groundwater. Groundwater occurs much below the zone of soil moisture. A porous and permeable formation capable of holding and transmitting a sufficient quantity of water under gravity (normal field condition) is an aquifer.

Why is soil important in watershed management?

Like human beings, plants too need the right kind and amount of sustenance for their growth and development. In addition to light, air, heat and water, plants require nutrients to synthesize their food. Soil acts as a storehouse for nutrients, which not only support plant life but also are an important determinant of crop productivity.

Agricultural lands lose their productivity very rapidly when they are subject to loss of topsoil due to erosion. Land rapidly deteriorates qualitatively due to poor soil management. Proper management of land (soil) therefore, assumes great importance, especially in a country like India where agriculture is the main occupation.

Soil erosion can affect crop growth in many ways. It can reduce soil nutrients and soil moisture-holding capacity due to loss of soil depth, soil organic matter and clay contents. It can also reduce available soil water due to increase in run-off, surface crusting, greater bulk and density of soil. Soil erosion can cause a reduction in rooting depth due to decreased top-soil depth; in soil microbes involved in nutrient recycling and soil aeration and in seed germination.

Soil erosion can also cause an increase in the washing away of seeds and fertilizer from the soil surface, thus increasing the amount of time that needs to be spent on farming operations. Variability in soil fertility can cause within-field variations in crop maturity, resulting in harvest loss.

The above effects of soil erosion on crop growth are iterative and cumulative in nature. The extent to which erosion actually reduces yield is also impacted by a number of other factors. Shallow-rooting crops tend to be more sensitive to the effects of erosion on yield. Crop management systems can, however, compensate for the effects of erosion on yields through increased fertilizer application, adoption of different cultivation practices and use of irrigation water.

How can soil erosion be prevented? What are the different approaches to conserve soil?

The principle of soil conservation is based on the adoption of methods that will make the soil more cohesive at its place of occurrence, thus making it less detachable in one hand and reduction of velocity of run-off and the wind, that leads to soil erosion, on the other. Conservation and management of rainwater plays the most important role in soil conservation. This is why soil and water conservation measures are generally dealt with together as a common activity.

Soil conservation is generally done through vegetational and mechanical measures. Vegetational measures include growing of trees, shrubs, grasses, crops etc. Vegetational measures can further be divided into two sub groups namely Agrostological practices and Agronomical practices like tillage operation, use of organic manure, crop rotation, strip cropping. Mechanical measures include construction of earthen, stone and masonry barriers and ditches for retarding velocity of run-off, as well as land levelling and construction of field bunds.

The vegetational measures take time to show results while mechanical measures give immediate result. From a sustainable watershed development perspective, vegetational measures are considered more permanent and/or sustainable than mechanical measures. In an ideal situation, mechanical measures are introduced simultaneously with vegetative measures so as to facilitate the vegetative measures to take their roots and replace the functions of most of the mechanical measures over the course of time. In arid regions, these measures serve the purpose of run-off harvesting while in humid regions, they retard the run-off to prevent soil erosion.

What are water harvesting structures and their types?

Rainwater harvesting (RWH) is a simple method by which rainfall is collected for future use. Water harvesting structures store rainwater or surface run-off; they are usually small in size for in situ use of tapped water e.g. field bunds, gully plugs, contour trench. Water retention or storage structures like reservoirs and tanks are generally larger structures, constructed for the purpose of storing large quantities of surface and stream run-off.

While large reservoirs are created by raising earthen bunds in large seasonal streams, small tanks may be created even by raising bunds across small and large gullies or depressions. From the construction point of view, all reservoirs and tanks have two main components, namely the earthen bund and the spillway. While the earthen bund is the structure which impounds the desired quantity of water, the spillway permits excess water to flow away, thus protecting the earthen bund from damage. Although the spillway or the waste weir should preferably be a masonry structure, a katcha outlet or pipe outlet may also be provided, particularly in the case of small tanks.

Therefore, water harvesting structures refer to all physical structures, small and big, constructed in the field for the purpose of storage of surface water flow. Large water retention structures require special engineering knowledge and skills for their design and construction. These are expensive, give immediate and visible results and have a limited life span. Smaller water retention structures are easy to construct, have longer effective life span and yield more sustainable results.

The different kinds of water harvesting structures are:

Surface tank: Tanks or reservoirs are constructed by impounding water in seasonal streams or in long elongated natural depressions (valleys).
Overflow weir: A weir is basically a gravity dam or a retention wall in which stability is obtained more from its own weight and buttresses are provided on the downstream side. To further reinforce its stability, a weir is generally anchored into a solid foundation.

How is the water requirement of crops measured?

Every crop requires a certain quantity of water during its period of growth. If rainfall is sufficient and timely, then no irrigation is required to raise a crop. Plants meet most of their water needs from rainfall. The need for additional water through irrigation is required only when there is no or inadequate rainfall, or when rainfall is distributed unevenly.

Plants can get their water requirement through a combination of irrigation, Effective Rainfall (EF) and Soil Water (SW) contribution in various proportions. Therefore,
WR = Effective Rainfall (ER) + Irrigation Water (IR) + Available Soil Water (SW)
Or, IR = WR – (ER + SW)

In other words, the minimum quantity of irrigation water required to be added to plants is equal to the crop’s Water Requirement (WR) less Effective Rainfall (ER) and available water in the soil (SW). Factors controlling irrigation requirement therefore depend broadly upon the climatological conditions (for consumptive use), soil conditions (for soil moisture status), crop types and irrigation management practices.

Why is afforestation needed in a watershed and how it can be accomplished?

Afforestation refers to planting of new trees. The major component of afforestation activity is the plantation of new seedlings. In an ideal situation, unless there is severe soil erosion and high biotic interference, forest lands can be restored through the process of natural regeneration by allowing the root stock already present in the land to grow, by providing adequate protection. But biotic interferences, i.e. the pressure on forest from man and animals, are ever increasing and must be dealt with by creating alternatives.

The very fact that forest degradation continues unabated is an indication that natural regeneration alone is unable to cope with the pressure and artificial planting is necessary to reverse the trend.

Several factors should be kept in mind while carrying out afforestation:

The needs of the local people;
The choice of tree and plant species;
Developing a nursery with ideal soil and moisture conditions that can raise healthy plants;
Advance preparation for seedling plantation;
Post plantation care for at least 5 years;
Fencing, proper watering and weed removal to protect the seedlings;
Preventive measures to ensure survival of the seedlings in the long term.

How is the skeletal plan of a watershed project formulated?

A project may be formulated on the basis of a skeletal plan (concept paper) developed after a PRA or after conducting an elaborate survey and investigation. A simple project proposal without necessary details is not likely to meet the criteria of a funding agency. Conversely, formulation of an elaborate project proposal down to its minute details without an assured source of funding is also untenable. Moreover, preparation of a very elaborate plan well in advance does not necessarily guarantee successful implementation of the project at a later stage. This dilemma needs to be navigated through discussions with the funding agency.

Most funding agencies have their own guidelines or formats for appraisal of a project proposal. In order to do a perfect job, especially while dealing with larger funding, these formats sometimes seek answers to many aspects of resource endowments and project implementation, much before the initiation of project formulation. For the sake of initial screening, a format should be made such that the answers to many of the queries can be provided meaningfully without going through the process of conducting an elaborate survey. A format which asks questions that cannot be answered without carrying out a detailed survey must be used only after a preparatory or an inception phase has been allowed and funded.

It is, however, prudent to first submit a proposal in a descriptive form (concept paper). A revised proposal may be submitted later in the standard format, which will eventually be supplied by the funding agency, if the proposal appears to them worth considering. While considering a project proposal, many funding agencies place emphasis on the project approach, based on which the project is formulated as well as implemented later. While some funding agencies may insist upon the adoption of a process approach, allowing the project to develop as it goes, others may prefer a well laid down work plan and monitoring plan in place following a Result Based Management approach.

Whatever the implementation strategy, necessary definitions and clarification of the basic elements of the project, viz. the project goal and purpose, beneficiaries, problem identification, location of the project area, funding requirement etc., is required in all cases.

What activities need to be initiated at different levels for adaptation and climate risk reduction?

Strengthen early warning systems
Increase capacity to prepare responses to climate risks
Increase capacity to manage water resources
Increase access and capacity to capture, store, treat and distribute water
Increase the resilience of agriculture and livestock
Increase the resilience of fisheries
Guarantee adequate levels of food security and nutrition
Increase the adaptive capacity of vulnerable people
Reduce people’s vulnerability to climate change related vector-borne diseases
Promote mechanisms for planting of trees, and establish forests for local use
Develop resilience mechanisms for urban areas and other settlements
Suit the development of tourist zones and coastal zones to reduce the impacts of climate change

What steps are recommended for involving communities in a watershed management project?

Conduct a Participatory Rural Appraisal (PRA) in the village to understand the problems and the solutions as perceived by the communities with respect to the management of their natural resources. The PRA must help the communities in bringing out a current resource utilization map for the entire village and a skeletal plan for both immediate and long term needs.
Conduct several planning workshops with the communities using extensive moderation technique to establish immediate and long term objectives i.e. the goal and purpose statements. This will eventually help in identifying the outputs that would be generated for achieving the project purpose.
If the project already has a project planning matrix prepared at the formulation stage for the purpose of project funding, improvise the same by incorporating the aspirations of the communities and get the final proposal approved by the funding agency. Form a committee from amongst the identified villagers which will undertake the responsibility of implementation of the final plan that has been developed through consensus.
Allow the implementation committee to prepare a broad work plan and review the same for improvements.
Arrange training for capacity building of the key persons.
Allow the community to implement as per their capability.
Provide technical assistance as per need.
Provide funds as per progress.
Introduce a monitoring mechanism (usually village meetings) so as to keep track of the extent to which the proposed outputs are being achieved. Introduce corrective measures to be arrived at through group discussions.

While formulating the rules, regulations and bylaws for the watershed committee, what aspects should be kept in mind?

Criteria for enrolment of membership to the committee.

Membership fee.
Sources of funds for the groups and the committee.
Procedures for electing Governing Body members of the committee.
Terms for the representatives, their designations, remunerations (if any) etc.
Responsibilities and rights of the elected representatives.
Sanctions to be used in case of non-fulfilment of obligations.
Periodicity, purpose and other conducting procedures.
Requirements for accounting and record keeping.
Rules which bind the groups, their contributions, obligations etc.
Basis for sharing of benefits from the project.
Grounds for expulsion of members, groups and elected representatives.
Objectives of the individuals, groups vis. a vis. the committee.

What should the structure of a watershed committee be like?

The project team should initiate the formation of the watershed committee and provide managerial inputs to sustain the committee during the project period. A watershed committee, to begin with should:

Operate informally under the leadership of a local leader.
Registration of the society under an appropriate act should be considered at an appropriate time
Have wider representation covering all sections of the communities keeping in mind the interests of women and the poorer sections
Be adequately represented by women
have the office bearers elected for a given term than be selected by the members in an informal meeting for an unspecified period
Have formal rules and regulations worked out and accepted by a majority.

What should be the procedure for functioning of the watershed committee?

Participation remains open, congenial where decisions are arrived at after taking opinions of all members into consideration;
Language used should be local and understood by all;
Decisions are taken by consensus;
Meetings take place on a fixed day of every month;
Attendance to the meeting made compulsory for the office bearers and open to all other members;
A working group be formed to analyse results, failures, improvements etc;
All important matters like the major activities, costs, benefits etc., be discussed;
Record of discussion be maintained.

What are the common problems in monitoring?

When a funding agency supports a large number of projects, it is likely that the funding agency will not be able to monitor all these projects, with equal attention. Some common problems encountered by such funding agencies are:

Shortage of trained and competent manpower. Monitoring is a specialised task. It requires persons with adequate perspectives and experience.
Inadequate inter-departmental cooperation and coordination on information exchange within the funding agency. Hard core subject matter specialists when involved in monitoring may tend to focus on matters related to their own expertise losing sight of other aspects, albeit of equal or greater importance.
Lack of coordination relating to the progress monitoring, process monitoring and financial monitoring. Not many staff are likely to be equally proficient in all the three areas.
Lack of institutional commitments. Sometimes, sufficient attention is not attached to monitoring because of the assumption that a good project implementing agency, in any case, will implement a project properly and vice versa. This leads to paying more attention on the pre-funding selection and appraisal process than actual on-line monitoring.
Poor standard of reporting. Many implementing agency fail to provide the necessary information in the desired format despite repeated orientation and reminder.
Lack of clarity in describing the project objectives and selection of corresponding performance indicators.

Joint monitoring workshops are useful to monitor a large number of similar projects as a group. Project Implementing Agencies (PIAs) are required to present their reports on certain common aspects e.g. progress made, problems faced, lessons learned, funds utilised, documentation prepared, contribution raised etc. When all the agencies report in a common format, it becomes possible not only to compare relative merits and demerits of each project but also to discuss common problems and seek solutions jointly.

India Water Portal is grateful to Dr Mihir Kumar Maitra for sharing the document with us, and allowing us to publish this in the public domain.

The full text of the document can be downloaded as a PDF from below: