Hydrological responses to forest cover change in mountains under projected climate conditions
Abstract
This study quantified the hydrological responses to the forest cover change in the upper part of Sola River basin, Forest Creek catchment, southern Poland, under projected climatic conditions. The Soil Water Assessment Tool (SWAT) will be applied to investigate the response of the hydrology regime to deforestation and reforestation processes. Under two emission scenarios (A1B and B1, IPCC) of the general circulation model GISS_E (NASA Goddard Institute) were employed to generate future possible climatic conditions . The detailed research was performed on a Forest Creek catchment during the 2002 -2012. A key point is to assess both the rate of change in hydrological conditions after the collapse of the spruce stands and the time necessary to stabilize the water management after the afforestation. The results of elaborations show that deforestation process reduces the retention by 40% (10 years), in the same time water drainage from the catchment shortened by 47% .
Keywords
Download Options
Introduction
Understanding the effects of de forestation and afforestation on the hydrological process is crucial to protecting water resources . Unfortunately, in recent years, in many parts of Europe, there has been a breakdown of forest stands as results of natural disaster or disease ( Bréda et. Al. 2006, Schütz et al. 2006, Svoboda et al. 2010, Durło 2012 ). The effect of mountain's forest on the hydrologic cycle is most clearly seen. Therefore, any disturbance in this zone determine the functioning of the hydrological system across the entire basin. The most dangerous situations arise when the forest ecosystem is rapidly falling, and the soil is denuded (Deng et al. 2010) . The damage of forest and conversion to cultivation , glades and coppice land increases stream flow and reduce of water retention. These results indicate that the stream flow dynamics are closely associated with rate of change in the environment and land use types within a watershed. Thus, this study is intended to provide a deeper understanding of the streamflow processes and useful quantitative information on land use changes in mountain catchments , enabling more informed decision -making in forest silvi culture and management (Huang et al. 2016) .The shape of the catchment i.e. topographic parameters and forest stability i .e. vegetation features have great influence on the water balance and runoff. The magnitude of reforestation on water yield varies as a function of vegetation type, climate, soil, also the rate of forest regeneration. Hydrological models, for example the Soil and Water Assessment Tool (SWAT), allow for simulating the hydrological effects of catchment features, which can help to understand the effects of land cover change on water yield in small mountain catchment (Srinivasan et al. 1998, Zhang et al. 2007, Wang et al. 20 08, Rahman et al. 2013, Huang et al. 2016 ).
Conclusion
The SWAT model was used to create a hydrological model of the Forest Creek (Silesian Beskid Mts.) catchment to investigate the effect of land use change and climate scenarios on its water regime. The analysis confirmed that the rate of changes of forest cover played a dominant role in catchment water balance. The effects of deforestation on the hydrological processes have been strengthened by changes in weather and climate change . Further -more, extreme weather may slow down reforestation process, in the case of unexpected disaster s forest regeneration has to start from the beginning. It is possible to improve the water balance conditions after ca. 50 -60 years, when young forest will reach density parameters to increasing retention. Based of pessimistic scenario (A1B, IPCC) , restoration of water balance stability will be delayed. Based on the results the main following conclusions can be drawn:
- Rapid deforestation contribute to huge reduction of water retention in shallow skelete podzolic soils , the change amounted to an average 47.5% during the decade 2010 -2012
- Rapid denude of the forest soils impart to significant increase in the water runoff speed, the change amounted to about 41.0% from 2002 to 2012
- The simulated and observed water balance indexes compares closely, thus shows a strong applicability of the SWAT model in accounting for these processes in small mountain watersheds.
- The very high coefficient of determination and efficiency obtained for monthly streamflow and water retention confirm that the performance of the SWAT on a monthly time step is excellent.