Mitigation of Impact of Climate Change through Watershed Management

Climate change during 21st century is projected to alter rainfall, and consequently the runoff and soil loss. The researchers worldwide are assessing the technical feasibility of the options to mitigate the impact of harmful gases (CO2, CH4 and others). The experiences gained by different institutions in India and worldwide have amply demonstrated the positive outcome of soil and water conservation measures implemented on watershed basis both under drought and abnormal rainfall conditions. Simple measures like strengthening of field bunds, contour bunding, trenching, vegetative barriers, agro-forestry, water harvesting and afforestation of denuded land along with other engineering and biological measures are found to be suitable options to mitigate the adverse impacts of climate change. These measures are, however, likely to be more expensive. Analysis showed that percent increase in the cross section of field bunds in medium soil is expected to be 33.3, 71.1 and 113.3% with an expected increase in one day maximum rainfall by 20, 40 and 60%, respectively, over the cross section corresponding to the one day maximum for the base period of 1961-1990. Similarly, the cross section of the field bunds in light textured soil is expected to be 30.9, 65.5 and 103.6% for the same increase in one day maximum rainfall. It is also projected that about 17% of additional earth work would be required in bunding (contour or graded) if one day maximum rainfall increases by 20 percent. Additional earthwork would increase to 80% with increase in rainfall by 100 percent. The earth work of trenching is projected to be directly proportional to the increase in daily rainfall. The analysis showed that the watershed management practices, though very effective mitigation options under adverse climatic conditions, are likely to be more expensive. To overcome the increasing cost of soil and water conservation measures, appropriate cost effective bio-engineering measures need to be evolved

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Not AvailableAppropriate soil conservation practices are essentially required in Indian Himalayan region to prevent degradation of natural resources. Thus erosion priority risk areas need to be identified to efficiently plan and execute conservation programmes. This study envisages to develop a strategy based upon the concept of partial area treatment by classifying erosion risk areas and prioritizing them upon the basis of existing erosion rates with targeted soil loss limits (T-value). The hypothesis is that highest priority for conservation action should go to such areas where the difference between potential erosion rate and the targeted limit is maximum so that available financial resources are efficiently utilized. The analysis indicated that about 25% of the total land area (TLA) in the north-western Himalayan region falls under severe or very severe erosion risk categories, especially where steeply sloping lands are under cultivation or overgrazed for decades. Only about 13% of TLA has T-value of> 10 Mg ha−1 yr−1 while about 30% area of the area is less prone to soil erosion. Within the region, Uttarakhand state has highest erosion risk area (58%) followed by Himachal Pradesh (48.5%). The concept of prioritization of erosion risk areas and their treatment with appropriate conservation measures was validated with the field data collected from two representative watersheds in the Himalayan region. The present approach can be easily extrapolated to other agro-climatic regions of the country to develop conservation master plans for efficient utilization of limited financial resources on sustainable basis.Not Availabl

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Not AvailableAPPROPRIATE SOIL CONSERVATION PRACTICES ARE ESSENTIALLY REQUIRED IN INDIAN HIMALAYAS REGION TO PREVENT DEGRADATION OF NATURAL RESOURCES. THE EROSION PRIORITY RISK AREAS NEED TO BE DIENTIFIED TO EFFICIENTLY PLAN AND EXECUTE CONSERVATION PROGRAMMES. THIS STUDY ENVISAGES TO DEVELOP A STRATEGY BASED UPON THE CONCEPT OF PARTIAL AREA TREATMENT BY CLASSIFYING EROSION RISK AREAS AND PRIORITIZING THEM UPON THE BASIS OF EXISTING EROSION RATES WITH TARGETED SOIL LOSS LIMITS (T- VALUE) . THE HYPOTHESIS IS TAHT HIGHEST PRIORITY FOR CONSERVATION ACTION SHOULD GO TO SUCH AREAS WHERE DIFFERENCE BETWEEN POTENTIAL REGION RATE AND TARGETED LIMIT IS MAXIMUM SO THAT AVAILABLE FINANCIAL RESOURCES ARE EFFECIENTLY UTILIZED. THE ANALYSIS INDICATED THAT ABOUT 25% OF THE TOTAL LAND AREA (TLA) IN THE NORTH- WESTERN HIMALAYAN REGION FALLS UNDER SEVERE OR VERY SEVERE EROSION RISK CATEGORIES , ESPECIALLY WHERE STEEPLY SLOPING LANDS ARE UNDER CULTIVATION OR OVERGRAZED FOR DECADES . ONLY ABOUT 13% OF TLA HAS T- VALUE OF >10 Mg HA-1 yr-1 WHILE ABOUT 30% AREA IS LESS PRONE TO SOIL EROSION . WITHIN THE REGION UTTARAKHAND STATE HAS HIGHEST EROSION RISK AREAS AND THEIR TREATMENT WITH APPROPRIATE CONSERVATION MEASURES WAS VALIDATED WITH THE FIELD DATA COLLECTION FROM TWO REPRESENTATIVES WATERSHEDS IN THE HIMALAYAN REGION . THE PRESENT APPROACH CAN BE EASILY EXTRAPOLATED TO OTHER AGRO- CLIMATIC REGION OF THE COUNTRY TO DEVELOP CONSERVATION MASTER PLANS FOR EFFICIENT UTILIZATION OF LIMITED FINANCIAL RESOURCES ON SUSTAINABLE BASIS

Hill water management: the way forward

In Palanisami, Kuppannan; Sharda, V. N.; Singh, D. V. (Eds.). Water management in the hill regions: evidence from field studies. [Outcome of the IWMI and ICAR Workshop organized by IWMI-TATA Water Policy Research Program]. New Delhi, India: Bloomsbury Publishing Indi

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Not AvailableA statistical assessment of curve fitting to soil water retention curve has been carried out for two different types of soils viz., Kharagpur sandy loam soil (four layers) and Black clay soil of Akola. The closed form equation describing soil water retention function of van Genuchten [VG (m, n) and VG (n)] and Brooks- Corey (BC) was fitted using RETC software and detailed statistical analysis was carried out to compare their performance. Results revealed that all the three models were found to perform reasonably well. The statistical analysis performed to discriminate the models such as R , AIC, t-value and RSS had showed a little difference among the models used for comparison. However, considering the relative ease at which the computation of hydraulic properties can be performed and the practical situation that can be accommodated, VG(n) is the best model among all the three models. This represents a simple closed form equation that can be derived to express the hydraulic conductivity function as compared toVG(m, n).Not Availabl

Water harvesting and recycling: Indian experience

Peer Revie