Comparative water balance study of forest and fallow plots

Abstract

© iForest -Biogeosciences and Forestry IntroductionThe relationship of vegetation cover and groundwater resources has drawn considerable scientific attention over the last decades. Many studies have shown that deforestation by logging or of natural origin (forest fire, wind damage) increased the average runoff from the affected area (e.g., Bosch & Hewlett 1982) and afforestation decreased runoff. Similar results were detected in recharge rates and groundwater depth, predominantly in dry regions. In Australia changes of vegetation from woodland to grassland or crops resulted in increases in recharge rates of one to two orders of magnitude (Maitre et al. 1999). The changes were largely due to the altered interception loss and the increased water extraction from the root zone. However, results of paired watershed research agreed only on the direction of the changes, not on their magnitude (Andressian 2004).Comparative water balance studies of forest and low vegetation covers have generally shown higher water use of forest cover (Ladekarl et al. 2005, Nachabe et al. 2005, Schilling 2007. Nachabe et al. (2005) analyzed the groundwater consumption in a shallow water table environment and estimated the annual ET for a forested area (1320 mm) and for a pasture (700 mm) using detailed soil moisture and water table monitoring. At the same time, a few studies have found negligible differences in evapotranspiration of different vegetation covers (e.g., Roberts & Rosier 2005). The latter study found that, although there were seasonal differences, on an annual basis the drainage below broadleaved woodland did not significantly differ from that below a pasture.Due to climate change, air temperature is expected to rise significantly during this century (IPCC 2007). As a direct consequence of warmer temperatures, the hydrological cycle will undergo changes with accompanying alteration in the rates of precipitation and evaporation. In Hungary, summer temperatures is expected to increase by up to four degrees by the end of this century, while precipitation is likely to increase in winter and decrease in summer (Gálos et al. 2007).The impact of climate change on groundwater resources was reviewed lately by Green et al. (2011). Although the uncertainty of predictions for change in groundwater recharge rates and discharge is large (e.g., future climate scenarios and groundwater extraction), numerous studies found that groundwater resources appear to be threatened by future climate change due to increased natural and human water demand.In light of the water balance uncertainties and the increasing pressures on groundwater resources due to future climate change, a comparative water balance study of an oak forest and fallow vegetation plots was initiated in a drought-threatened lowland environment in north-eastern Hungary. Water balance components were estimated by the Hydrus 1-D numerical model (Simunek et al. 2005), calibrated on measured soil moisture and groundwater levels.Our research questions were the following: (1) what is the m...

Dynamics, Hydrological Relations and Pollution of Precipitation and Flood Waters in a Forest Ecosystem

“…A significant and negative correlation was found between potential evapotranspiration and the level of ground water at depths of 1.5 m and 2.5 m. An increase in the amount of potential evapotranspiration increases water consumption and reduces soil moisture, thus reducing ground water stocks in lowland forests. These results confirm the results of comparative water balance study in Hungary [26]. They stated that during periods of drought, the share of water consumption from ground waters in English oak forests was up to 90% of the amount of transpiration, while during wet weather, water consumption from ground water was significantly lower.…”

Groundwater uptake of different surface cover and its consequences in great Hungarian plain

“…4), indicating a depression in the water table beneath the trees. The magnitude of the differences was similar to the water table depression determined during the growing season by Nosetto et al (2007) on a planted oak forest and adjacent grassland in the Hortobágy region (0.26-0.60 m) and those determined by Móricz et al (2012) by comparing an oak stand and a fallow plot in Nyírség (0.5-0.6 m). Both regions (Hortobágy and Nyirség) are also located in the Hungarian Great Plain.…”

“…A good example for comparing the water balance of different land uses is the analysis of Móricz et al (2012) in Nyírség. In that paper, a common oak forest has 30% more ET (758 mm/year) than a neighbouring fallow (623 mm/ year).…”

Water and Carbon Footprint of Wine: Methodology Review and Application to a Case Study

“…The initial depletion (D r,0 ) is equal to the depletion at the end of the previous year, and it is 0 for the cases presented in this work. Deep percolation is zero if the water content in the rooting zone is below field capacity, otherwise it is given by DP i " P eff,i`Ii´E T a,i´Dr,i-1 (12) The effective precipitation (mm) is the fraction of rainwater that reaches the rooting zone [43] P eff,i " P i´α¨L AI¨˜1´1 1`f sc¨Pi α¨LAI¸(…”