Development of Drought Severity – Areal Extent – Frequency Curves in The Parambikulam - Aliyar Basin, Tamil Nadu, India

Abstract

Assessment and characterization of regional droughts provide useful information for sustainable water resources planning and management. In the present study, the Standardized Precipitation Index (SPI) a most widely used rainfall based drought index was applied to investigate the temporal characteristics, areal extent and frequency of meteorological drought in the Parambikulam-Aliyar basin, Tamil Nadu. For this purpose, the basin was divided into 97 grid-cells of 5 × 5 km with each grid correspondence to approximately 1.03% of total area. Gridded monthly rainfall was developed by spatial interpolation technique with the help of GIS capabilities at each grid point using monthly rainfall data for the period of 40 years (1972-2011) from 28 rain gauge stations. Regional representative of SPI values calculated from spatially averaged mean areal rainfall were used to characterize the temporal variation of drought. Drought severity-areal extent-frequency (SAF) curves were constructed using gridded SPI values to assess the drought severity and areal extent with respect to return period so as to describe and characterize the spatial and recurrence patterns of drought. The analysis of SPI suggests that the basin suffered severe droughts in the 1970s, 1980s and 2000s. The SAF curves developed in this study can be used for the development of a drought preparedness plan in the region and planning sustainable water resource management within the basin.

Procena i karakterizacija regionalnih suša daju korisne informacije za održivo planiranje i upravljanje vodenim resursima. U ovom istraživanju primenjen je Standardizovani indeks padavina (SPI), kao najšire primenjeni indeks suše zasnovan na padavinama, za ispitivanje vremenskih karakteristika, prostornog oblika i učestalosti suše u basenu Parambikulam-Aliyar, Tamil Nadu. Za ovu svrhu basen je podeljen na 97 mrežnih ćelija dimenzija 5 × 5 km, tako da svaka ćelija odgovara približno 1.03% ukupne površine. Mesečne padavine u mreži razvijene su tehnikom prostorne interpolacije uz pomoć GIS-a u svakoj tački mreže korišćenjem podataka o mesečnim padavinama za period od 40 godina (1972-2011) iz 28 mernih stanica. Regionalne reprezentativne SPI vrednosti izračunate iz prostorno prosečnih vrednosti padavina korišćene su za karakterizaciju vremenskih varijacija suše. Krive suše-prostornog položaja-učestalosti (SAF krive) su konstruisane korišćenjem mrežnih SPI vrednosti za procenu jačine suše i prostornog položaja u odnosu na povratni period, tako da se opišu i karakterišu prostorni i povratni oblici suše. Analiza SPI vrednosti pokazuje da su basen pogodile jake suše 1970-tih, 1980-tih i 2000-tih. Razvijene SAF krive mogu se koristiti za razradu plana pripravnosti u sušnim periodima u regionu i planiranje održivog upravljanja vodenim resursima u basenu.