CS(AR)-1/2008-09 : A comprehensive Watershed Management Plan for a Degraded Watershed in Bundelkhand Region of Madhya Pradesh

Abstract

The challenge of managing environments becomes more complex as populations expand, various demands on natural resources increase and new technologies are developed, that knowingly or unknowingly destroy the environment. The restoration and maintenance of the physical, chemical and biological integrity of the environments require decision making that balance human and natural systems. Watershed management is increasingly being recognized by policy makers, resource managers, and communities as an effective way to achieve multiple goals substantially. The goal of watershed management is to plan and work towards an environmentally and economically healthy watershed that benefits all the stakeholders. Problem solving is a vital part of the watershed management, wherein a particular issue is addressed within the scope of wider landscape and ecosystem connections, in search for appropriate solutions. Watershed management planning and its proper implementation help in uplifting the socio-economic condition of habitants and upgrade the preservation of environmental regime. Watershed management program aims at integrated development since each sector of watershed is inter-linked with the other. While hydrology is an essential component, the land productivity is an equally important integral part of the watershed management process. Thus watershed management deals not only with the protection of the water resources but also with the capability and suitability of land and vegetative resources to be managed for the sustainable development.

The watershed analysis includes water budgeting studies, land capability classification, soil loss estimation, assessment of irrigation water requirement, watershed modelling, watershed prioritization, development of flood hydrographs using GIUH techniques, identification of sites for storage structures, selection of zones for artificial recharge, development of an alternative land use plan, irrigation water requirement for changed land use plan, suggestions for site specific soil and water conservation measures and assessment of its impact on the soil erosion and runoff processes in the watershed. The water budgeting of Tumri watershed reveals that rainfall is the major inflow component whereas surface runoff is the major outflow component and about 8.05 MCM water flows through the streams in a normal rainfall year which can be tapped at suitable sites within the watershed so as to provide the much required irrigation water. The land capability classification has helped to identify' land capability classes II to VII in the watershed and the capability classes II to IV are suited for agriculture whereas classes V to VII are not suited for agriculture.

Effective control of soil erosion requires an ability to predict the amount of soil loss, which would occur under alternate management strategies and practices. The Universal Soil Loss Equation (USLE) model has been applied to estimate soil loss from the watershed. The average soil loss from the watershed is 14.60 t/ha/year under the present land use and no conservation practices. Sensitivity analysis indicates that treatment measures on the agricultural land alone would reduce the rate of soil erosion from the current 14.60 t/ha/year to 11.52 t/ha/year. The irrigation water requirement of different crops in the watershed has been computed for the present cropping pattern and the gross irrigation water requirement during kharrif and rabi season is 1,058 and 5.169 MCM respectively.

Runoff is one of the important hydrologic variables used in most of the water resources applications. The SCS-CN model has been applied for gauged Nala subwatershed and Tumri watershed and is able to simulate the flows with an efficiency of 80% and 93% in 2007-08 and 2008-09 respectively. The SCS-CN model has also been applied to the ungauged Tumri watershed and the seasonal surface runoff is estimated to be 8.05 MCM, 2.49 MCM and 7.23 MCM for the 2006-07 to 2008-09. The model can be used to estimate the surface runoff in future years on the basis of the observed daily rainfall in the watershed which can be used for planning of development of new water resources projects in the watershed.

Before taking up any watershed management program, first question arises that which area should be treated first and watershed prioritization helps to identify the stressed areas of watershed where immediate measures are required: The watershed has been divided into 19 sub-watersheds for prioritization and SW-8, SW-9, SW-11, SW-15, SW-16, SW-18 and SW-19 have been identified as the very-high and high priority watersheds and conservation measures should be initiated in these sub-watersheds immediately on a priority basis followed by treatment measures on moderate and low priority sub-watersheds. GIUH based Clark model have been used for the development of flood hydrographs for few storms in gauged Nala sub-watershed and ungauged Tumri watershed which will be useful for estimation of design flood in watershed. The parameters of the Clark model have been computed using geomorphological characteristics of the basin. The RMSE between the observed and computed flood hydrographs for few storm events varies between 0.11 to 1.83 for Nala sub-watershed.

The rugged topography and the location of the Tumri watershed in the upstream reaches of river Sonar limits the construction of medium or major water resources projects and as such small water storage structures are feasible for such terrain which require less investment and do not require clearances from various agencies. Seven well distributed sites have been identified in the watershed to create small water storage structures based on certain decision rules. The salient features of all the storage schemes including the elevation-area and elevation capacity curves have also been provided along with the priority analysis of these structures. Zones favourable for artificial recharge have also been demarcated after the analysis based on slope, land use, water table fluctuation, hydro geomorphologic characteristics. The analysis helps to identify 33.08 hectare as the most suitable zones for artificial recharge and various direct and indirect techniques of artificial recharge can be employed here.

Based on the best possible use and limitations of the land, an alternative land use plan has been developed for the watershed to take care of the various demands of the watershed community. Thrust has been given to increase the agricultural area based on suitability of land and availability of additional water in the storage structures. The barren and degraded lands may be used for developing grazing lands and agro forestry; and plantations may be encouraged in open forests to slowly convert them into dense forests with good canopy which will reduce the soil erosion to a great extent. Various area specific soil conservation measures including agronomic, mechanical, chemical and biological measures have been suggested for agricultural lands, grazing lands, agro forestry lands and forests, Similarly water conservation measures have been recommended separately for agricultural lands and forests.

The revised irrigation water requirements have been estimated based on the suggested land use plan for the watershed and the gross irrigation water requirement for crops is expected to increase from 1.056 MCM to 1.788 MCM m kharrif season whereas 6.533 MCM water is required for irrigation instead of 5.619 MCM in rabi season. The irrigation scheduling plan can be worked out on the basis of the computed ten-daily water requirements. The impact assessment analysis of the conservation measures and management strategies have been carried out to asses the impacts on soil erosion and water resources scenario in the watershed. The analysis indicates that the reduction in seasonal surface runoff varies between 16.1% and 54.6% whereas the soil loss from the watershed may reduce considerably to 1.33 t/ha/yr, if the suggested land use plan and recommended soil and water conservation measures are adopted in Tumri watershed. The study has tried to touch upon all the important elements responsible for various processes and a comprehensive plan has been prepared for the watershed which if implemented effectively can definitely arrest the ecological degradation and improve the overall health of the watershed and living conditions of the local inhabitants.