Watershed Management | Geography Optional for UPSC (Notes) PDF Download

Introduction

• Watershed is defined as any surface area from which rainfall is collected and drains through a common point.
• It is synonymous with a drainage basin or catchment area. In other words, watershed is a geo-hydrological unit, comprising of all land and water within the confines of drainage divide.
  
  Watershed Management
• The size of watershed may vary from a few hectares to several thousands of hectares. Watershed sizes are classified into three: micro, mini, and macro watersheds. In fact, watershed is a biological, physical, economic and social system. It is a land mass bounded vertically by the area influenced by human activities and horizontally by the water that drains into a point in the channel.
• Watershed management is the integration of technologies within the natural boundaries of a drainage area for optimum development of land, water, and plant resources to meet the basic needs of the people and animals in a sustained manner.

Principles of Watershed Management

• Utilizing the land according to its capability based on land use classification.
• Conserving as much rainwater as possible at the place where it falls i.e., in situ conservation.
• Draining out excess water with a safe velocity and diverting it to storage structure (farm ponds, tanks) for future use.
• Avoiding gully formation and putting up check-dams at suitable places to control soil erosion, to store rainwater, and recharge groundwater.
• Identifying a suitable cropping pattern for the watershed area.
• Maximizing productivity per unit area, per unit time, and per unit water.

Objectives of Watershed Management

• To effectively conserve soil, rainwater, and harness the surplus water to create water sources in addition to groundwater recharge.
• To promote sustainable farming and stabilize crop yield by adopting suitable cropping and crop management systems.
• To cover non-arable areas effectively through afforestation, horticulture, and pasture land development based on the capability of the land.
• To enhance the income of the individuals by adopting alternative enterprises.
• To restore ecological balance.
• Increasing cropping intensity and land equivalent ratio through intercropping and sequence cropping.
• Safe utilization of marginal and wastelands through alternate land-use systems such as agro-forestry.
• Ensuring sustainability of the ecosystem benefiting the man-animal-plant-land-water complex in the watershed.
• Stabilizing total income and cutting down the risk of during aberrant weather situations.
• Improving infrastructural facilities with regard to storage, transportation, and marketing.
  
  Pong Approach

Planning For Watershed Management

• Comprehensive planning for watershed management starts with obtaining suitable maps through remote sensing techniques.
• Remote sensing provides a synoptic picture of the watershed for the characterization of natural resources, land, water, vegetation, and inter-relationship between them. Besides mapping natural resources, satellite imagery can give the estimate of the area covered by major crops, crop yield, area affected by pests and diseases and drought conditions, if any. The location of structures like check-dams, farm ponds etc., can also be delineated using satellite imagery pictures.
• Distribution patterns and assessments of the status of material resources can be obtained from satellite pictures. Comprehensive planning of various activities is then carried out. Mechanical, agronomical, agro-ecological and forestry measures of soil and rainwater conservation are then planned and implemented.

Case Study

• On July 27, 2016, rain for only two hours paralyzed the life in Gurgram (Gurgaon), with deep waterlogging. The main cause of this tragedy was ill-conceived planning. In the planning of Gurgram, Watershed Planning was ignored.
• The Firozpur-Jhikra-Delhi ridge forms the western boundary and the Delhi ridge forms the eastern boundary of this watershed. The natural drainage pattern of the city comprises of large depression and streams, tending to cover inland instead of flowing into the Yamuna.
• The Delhi-Jaipur Highway No. 8 crosses several watersheds almost in the middle and blocks the natural drainage pattern from south to north. Thus, the unscientific planning of National Highway No. 8 is largely responsible for the Gurgram tragedy. It is thus, important to incorporate the watershed approach in the planning of a city.

Delineation and Codification of Watersheds

• The All India Soil and Land Use Survey Organization of the Department of Agriculture, Government of India, has finalized a nationwide system of delineation and codification of watersheds. According to this scheme various size of the watershed have been divided into:
  • Basins
  • Catchments
  • Sub-catchments
  • Watersheds
• In India, there are 35 rivers, 112 catchments, 500 sub-catchments, and 3200 watersheds. For the purpose of planning and development, the 3200 watersheds have been divided on the basis of the area into the following three categories:
  • Sub-watersheds( 10,000 to 50,000 hectares)
    (i) Milli-Watershed ( 1000 to 10,000 hectares)
    (ii) Micro-Watershed ( 100 to 1000 hectares)
    (iii) Mini-Watershed ( 1 to 100 hectares)

Significance of Watershed Management

• Watershed management is a comprehensive program to utilize the available water and other resources in such a way that:
  • The productivity of agriculture is enhanced
  • To protect and enhance water resources, moderate floods and reduce silting up of tanks and conserve rainwater for crops and thus mitigate droughts
  • To utilize the natural local resources for improving cottage and small industries to improve socio-economic conditions of local people.
  • The allied activities of industries are promoted
  • Social forestry provides an additional source of income
  • Soil erosion is checked
  • Cottage industries are developed
  • More employment opportunities are created
  • The space available may be made more enjoyable, and ecology may be maintained in a healthy and sustainable condition.