| Description |
The goal of this study was to analyze precipitation patterns in five different climatic regions across the country of India, to determine if rainwater harvesting (RWH) could provide sufficient indoor water for a typical household. Data were acquired from the United States National Aeronautics and Space Administration (NASA) Tropical Rainfall Measuring Mission (TRMM) satellite for this study. For the study, six cities were selected in five different climatic regions based on the Koppen climate classification. Three-hour increment precipitation average intensities were extracted from TRMM_3B42 files for the centroid of each city. The analysis applied a water balance approach, with inflows estimated as runoff from the rooftop catchment and outflows estimated from water demand. Cistern sizes were varied from 757 to 18,927 liters and the catchment area was varied from 10 to 100 m3 to quantify the performance of RWH across a range of system design conditions. As a result of the monsoonal climate in India, highly seasonal precipitation patterns occur. To study the seasonal precipitation influence, a dry-to-wet ratio was calculated as the average volume of precipitation for the months of June through August divided by the average volume of precipitation for the months of September through May. The Water Saving Efficiency (WSE) metric was calculated for each city on a yearly basis. The WSE values for each city were analyzed with the dry-to-wet ratios and precipitation volumes. The WSE varied from 2% to 6% for the smallest catchment area and cistern volume, to 20% to 50% for the largest catchment area and cistern volume. Overall, the larger the area available and the larger the cistern, the higher the efficiency; however, for small catchment areas, the increases in cistern volume provided no additional benefit. A low dry-to-wet ratio resulted in a moderate efficiency if the precipitation volume was high, and a high dry-to-wet ratio resulted in a poor efficiency if the precipitation volume was low. Synthesizing the results, the general conclusion from this study is most cities in India will realize benefits from rainwater harvesting for urban water supply. |
