A conceptual model of daily water balance following partial clearing from forest to pasture

Abstract

Abstract.A simple conceptual water balance model representing the streamflow generation processes on a daily time step following land use change is presented. The model consists of five stores: (i) Dry, Wet and Subsurface Stores for vertical and lateral water flow, (ii) a transient Stream zone Store (iii) a saturated Goundwater Store. The soil moisture balance in the top soil Dry and Wet Stores are the most important components of the model and characterize the dynamically varying saturated areas responsible for surface runoff, interflow and deep percolation. The Subsurface Store describes the unsaturated soil moisture balance, extraction of percolated water by vegetation and groundwater recharge. The Groundwater Store controls the baseflow to stream (if any) and the groundwater contribution to the stream zone saturated areas. The daily model was developed following a downward approach by analysing data from Ernies (control) and Lemon (53% cleared) catchments in Western Australia and elaborating a monthly model. The daily model performed very well in simulating daily flow generation processes for both catchments. Most of the model parameters were incorporated a priori from catchment attributes such as surface slope, soil depth, porosity, stream length and initial groundwater depth, and some were calibrated by matching the observed and predicted hydrographs. The predicted groundwater depth, and streamflow volumes across all time steps from daily to monthly to annual were in close agreement with observations for both catchments.

Disconnection of groundwater from surface water causes a fundamental change in hydrology in a forested catchment in south-western Australia

“…Variable source areas are formed when perched or permanent groundwater tables intersect the ground surface. Saturation excess runoff from variable source areas is considered to be an important mechanism of streamflow generation in the jarrah forest (Stokes, 1985;Ruprecht and Schofield, 1989; Bari and Smettem, 2006). Ruprecht and Schofield (1989) found that, following clearing of Wights catchment in the high rainfall zone of the jarrah forest for agriculture, a significant component of the increased streamflow was correlated with expansion of the groundwater-induced variable source area.…”

Assessing climate change impacts on water balance in the Mount Makiling forest, Philippines

“…In hydrologic modelling, many researchers have discussed the use and application of different hydrologic models such as water balance, regression analysis, energy budget and other empirical models (Tabios 1978;Arnell 1999;Vogel et al 1999;Fleming and Neary 2004;Young 2006; Bari and Smettem 2006). The application of a typical hydrologic model requires calibration and parameter fitting for a given site.…”

Multiple environmental services as an opportunity for watershed restoration

“…In this paper we explore the concept of PES for improvements in water quality brought about by reforestation, in the Warren-Tone watershed (WT) of south-west Western Australia, which has a well-calibrated hydrological response model (LUCICAT) (Bari and Smettem, 2006a, b). LUCICAT has consistently provided good estimates of monthly streamflow, with Nash-Sutcliffe Criteria over 0.8 in all cases and over 0.9 for over 80% of watersheds modelled (Bari and Smettem, 2006a). The LUCICAT hydrological model provides two major outputs: water yield and water quality in response to landuse.…”