SPATIO-TEMPORAL VARIABILITY OF RAINFALL & STREAMFLOW MODELING FOR A PENINSULAR BASIN IN INDIA

Abstract

Climate change is recognized to be one of the most serious challenges facing mankind today. Driven by anthropogenic activities, it is known to be a direct threat to our food and water supplies and an indirect threat to world security. Increase in the concentration of carbon dioxide and other greenhouse gases in the atmosphere will certainly affect hydrological regimes. The consequent global warming is expected to have major implications on water resources management. The increasing rate of global surface temperature is going to have significant impact on local hydrological regimes and thus on water resources, this leads to the assessment of water resources potential resulting from the climate change impacts. Main parameters that are closely related to the climate change are temperature, precipitation and runoff. Therefore, there is a growing need for an integrated analysis that can quantify the study of climate variability & its arising consequences on water resources. In present study, Statistical trend analysis has been carried out on monthly, seasonal and annual scale using Parametric (Regression analysis) and non-parametric (Mann-kendall & Sen’s Slope Estimator) methods. Drought is a weather related natural hazards In fact, drought is complex and least understood of all natural hazards, affecting more people than any other hazard. Among all these kinds of droughts, only Meteorological drought is important from our study point of view. The Standardized Precipitation Index (SPI), which is one of the most commonly used and recommended drought indicator, is used to describe meteorological droughts. It was designed to enumerate precipitation deficit for multiple timescales. There are many indices to measure meteorological dryness, such as simple rainfall devation from historic norms, palmer drought severity index (PDSI) and standardized precipitation index (SPI). Among these indices, SPI has been widely used in recent years because of its computational simplicity and reliable interpretation. In our study, Standardized Precipitation Index (SPI) has been used for drought characterization in Chaliyar basin. The study presented in this paper constitutes an initial approach to the problematic task of evaluating the spatial variation of ground water levels. In our study, spatiotemporal analysis of groundwater level fluctuations of 29 piezometric wells using geostatistical analysis was performed for chaliyar river basin. Geostatistical analysis was performed using ordinary kriging method in Arc GIS & finally the spatial prediction maps of water level were generated. Our study describes the application of NAM (NedborAfstromnings Model), to investigate its performance, efficiency and suitability in Chaliyar river basin of kerala. It is deterministic, lumped and conceptual rainfall-runoff model that operates by continuously accounting for the moisture content in three different and mutually interrelated storages that represent overland flow, interflow and base flow. In the present study, the rainfall-runoff model has been developed, calibrated and validated using flow data at a river gauge station Kuniyil, in the Chaliyar River Basin, Kerala, India. In brief, the present work intends to study climatic variability in the Chaliyar River Basin through (1) Precipitation Trend Analysis (2) Drought Characterization. (3) Study of Spatial Variation of Ground Water levels & (4) Rainfall-Runoff Modelling.