*3.1. GIS Landuse Analysis*

The land use factors developed using GIS analysis [29] essentially indicate the percentage contribution of each land use to the total catchment area or watershed area. The three dominant land use factors are ULUF (urban land use factor), FLUF (forest land use factor), and ALUF (agricultural land use factor). They are given by

$$LILIF = \sin^{-1}\sqrt{\text{urlban area} / \text{ wartershed area}} \tag{1}$$

$$FLILF = \sin^{-1}\sqrt{fores \, area / \, water \, shell \, area} \tag{2}$$

$$ALILF = \sin^{-1}\sqrt{\text{gravitational area}/\text{waterhead area}}\tag{3}$$

Moreover, the above definitions have several advantages as compared to the land uses by simple fractions. The arcsine transformation helps in making the land use distribution near-normal or Gaussian. This transformation gives the values in radians proportional to the angle subtended at the center on a pie chart of land uses [25]. The transformation is known to stabilize the variance and scales the proportional data [30–33].
