Watershed management and its importance
Watershed is a geographical area drained by a stream or a system connecting stream in which water from all over an area flow under gravity to a common drainage channel. A watershed system delivers water through rills, gullies and streams to a larger body of water.
Watershed management is proper utilization of land and water resource for optimum production with minimum hazards to natural resources. It relates to soil and water conservation proper land uses, promote afforestation and sustainable farming practices, conserve farmland and pastureland, maintaining soil fertility, proper management of local water for farming, drainage, construct small dams for flood protection, improving individuals standard of living and thereby promote ecological balance.
Watershed plans should first identify the characteristics of the watershed and inventory the watershed’s natural resources. The first steps in watershed management planning are to:
i. Delineate and map the watershed’s boundaries and the smaller drainage basins within the watershed.
ii. Map and prepare an Inventory of resources in the watershed. Prepare an Inventory and map the natural and manmade drainage systems in the watershed.
iii. Prepare an Inventory and map land use and land cover.
iv. Prepare a soil map of the watershed
v. Identify areas of erosion, including stream banks and construction sites.
vi) Identify the quality of water resources in the watershed as a baseline; and
Watershed development project in the country has been sponsored and implemented by Government of India from early 1970s onwards. Various watershed development programs like Drought Prone Area Program (DPAP), Desert Development Program (DDP), River Valley Project (RVP), National Watershed Development Project for Rain-fed Areas (NWDPRA) and Integrated Wasteland Development Program (IWDP) were launched subsequently in various hydro-ecological regions. Entire watershed development programs primarily focused on soil conservation and rainwater harvesting during 1980s and before.
Millions of people throughout the world do not have access to clean water for domestic purposes. In many parts of the world conventional piped water is either absent, unreliable or too expensive. One of the biggest challenges of the 21st century is to overcome the growing water shortage. Rain Water Harvesting (RWH) has thus regained its importance as a valuable alternative or supplementary water resource, along with more conventional water supply technologies. Water shortages can be relieved if rain water harvesting is practiced more widely.
i. To overcome the situation of inadequacy of water supply.
ii. The most economical way to increase the ground water table.
iii. To replenish the sub soil of the urban area covered with pavements.
iv. To recharge the underground water table at places where the availability of rain water is higher or to overcome the situation of water logging.
v. Rain water harvesting also improves the quality of underground water through a process called dilution.
vi. To get water for irrigation of greenbelts, farms, gardens, etc.
There are two main techniques of rain water harvestings:
1. Storage of rain water on surface for future use.
2. Recharge to ground water.
The storage of rain water on surface is a traditional technique and structures used were underground tanks, ponds, check dams, weirs, etc. Recharge of ground water is a new concept of rain water harvesting and the structures generally used are: Recharge pits filled with boulders, gravels, and coarse-sand, Wells, Trenches etc.