is when overland flow is decreasing back to ambient levels. In higher drainage systems, the overland flow reaches the channels quicker resulting in a narrower spread in the falling limb. Baseflow is the other contributor to the hydrograph. The peak of baseflow to the channels will occur after the quick-flow peak because groundwater flow is much slower than quick-flow. Because the baseflow peak occurs after the quick-flow peak, the baseflow peak influences the shape of the falling limb. According to the proportionality put forth by Gregory and Walling, as drainage density increases, the contribution of baseflow to the falling limb of the hydrograph diminishes. During a storm event in a high drainage density basin, there is little water that infiltrates into the ground as infiltration because water spends less time flowing over the surface in the catchment before exiting through the central channel. Because there is little water that enters the water as infiltration, baseflow will contribute only a small part to falling limb. The falling limb is thus quite steep. Conversely, a low drainage system will have a shallower falling limb. According to Gregory and Walling’s relation, the decrease in drainage density results in an increase in baseflow to the channels and a more gradual decrease in the hydrograph. Formula for drainage density Montgomery and Dietrich (1989) Montgomery and Dietrich (1989) determined the following equation for drainage density by observing drainage basins in the Tennessee Valley, California: Where ws is the mean source width, ρw is the density of water, R0 is the average precipitation rate, W* is the width of the channel head, ρs is the saturated bulk density of the soil, Kz is the vertical saturated hydraulic conductivity, θ is the slope at the channel head, and φ is the soil angle of internal friction. R0, the average precipitation term, shows the dependence of drainage density on climate. With all other factors being constant, an increase in precipitation in the drainage basin results in an increase in drainage density. A decrease in precipitation, such as in an arid environment, results in a lower drainage density. The equation also shows the dependence on the physical characteristics and lithology of the drainage basin. Materials with a low hydraulic conductivities, such as clay or solid rock, would result in a higher-drainage density system. Because of the low hydraulic conductivity, there is little water lost to infiltration and that water exits