Local climate and water availability changes due to landscape modifications

Abstract

Water availability is a crucial problem for many countries and will become more important in the context of global change, particularly for arid and semiarid regions. The water cycle is linked to natural processes but is also strongly influenced by human activities, in particular land-use changes. Since evapotranspiration is highly dependent upon vegetation characteristics and landscape structure, different land-use distributions are expected to have a significant influence on evapotranspiration rates. The fundamental paradigm on which this analysis is based is that landscape pattern, functional interactions among landscape elements, and natural and anthropogenic changes in structural relationships are intimately related. In order to assess the impact of landscape structure on local climate and water cycle variables, we set up a series of numerical experiments for July 1997 over a domain that broadly corresponds to Castilla-La Mancha, a region of southeastern Spain (364 × 280 km2). We use a regional climate model (ClimRAMS) with nested grids of 14 km and 3.5 km cell ;size, implemented with a USGS global database of elevation and land cover, and the FAO soil classification database. Landscape changes are applied on a 112 × 84 km2 sub-domain (the 3.5 km grid). We developed different landscape structure scenarios by considering changes in landscape composition (type and extent of ecosystems) and configuration (spatial arrangement of ecosystems). Changes as large as IK in daily average air temperature and 9.5K in daily temperature range take place when replacing mixed forest with semi-desert over the whole sub-domain. For analyzing impacts within each landscape scenario, we concentrate on grid cells that have the same land cover between two scenarios. For example, we looked at a forested cell in two scenarios with same land composition (50% mixed Natalia Hasler et al. forest — 50% semi-desert) but with a different spatial configuration of the landcover types. Differences in evapotranspiration between the two scenarios in that particular gird cell reached 12.5 mm of evapotranspiration (15% of total amount). The number of water stress days also differ in these kinds of grid cells. This study demonstrates that changes in landscape structure can have a significant impact on moisture budgets in arid regions.KeywordsSoil MoistureLand CoverGrid CellRegional Climate ModelLatent Heat FluxThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.