Statistical low flow estimation using GIS analysis in humid montane regions in Puerto Rico

• Published in: Water resources bulletin (Urbana) Vol. 32; no. 6
• Main Authors: Garcia-Martino, A.R. (USDA, FS, International Institute of Tropical Forestry, Rio Piedras, Puerto Rico.), Scatena, F.N, Warner, G.S, Civco, D.L
• Format: Journal Article
• Language: English
• Published: 01.12.1996
• Subjects: BASSIN VERSANT; BOSQUES; CUENCAS HIDROGRAFICAS; DEBIT; FORET; GASTO; HIDROLOGIA; HYDROLOGIE; MATEMATICAS; MATHEMATIQUE; METHODE STATISTIQUE; METODOS ESTADISTICOS; MODELE MATHEMATIQUE; MODELOS MATEMATICOS; PARC NATIONAL; PARQUES NACIONALES; PORTO RICO; PUERTO RICO; REGION D'ALTITUDE; SISTEMAS DE INFORMACION GEOGRAFICA; SYSTEME D'INFORMATION GEOGRAPHIQUE; ZONA DE MONTANA; ZONA HUMEDA; ZONE HUMIDE
• ISSN: 0043-1370
• DOI: 10.1111/j.1752-1688.1996.tb03495.x

Statistical analysis of watershed parameters derived using a Geographical Information system (GIS) was done to develop equations for estimating the 7d-10 yr, 30d-10 yr, and 7d-2 yr low flow for watersheds in humid montane regions of Puerto Rico. Digital elevation models and land use, geology, soils, and stream network coverages were used to evaluate 21 geomorphic, 10 stream channel, 9 relief, 7 geology, 4 climate, and 2 soil parameters for each watershed. To assess which parameters should be used for further investigation, a correlation analysis was used to determine the independence and collinearity among these parameters and their relationship with low flows. Multiple regression analyses using the selected parameters were then performed to develop the statistical models of low flows. The final models were selected in the basis of the Mallow Cp statistic, the adjusted R2, the Press statistic, the degree of collinearity, and an analysis of the residuals. In the final models, drainage density, the ratio of length of tributaries to the length of the main channel, the percent of drainage area with northeast aspect, and the average weighted slope of the drainage were the most significant parameters. The final models had adjusted standard errors of 58.7 percent, 59.2 percent, and 48.6 percent for the 7d-10 yr, 30d-10 yr, and 7d-2 yr low flows respectively. For comparison, the best model based on watershed parameters that can be easily measured without a GIS had an adjusted standard error of 82.8 percent