Land Use and Land Cover Changes and Their Impacts on Hydroclimate, Ecosystems and Society

Abstract

This chapter presents recent advances in the understanding of the effect of land cover/land use changes on the hydrologic cycle, and identifi es current gaps in the knowledge needed for useful decision-making and water resource management. Research achievements within a framework of Earth System Models (ESM) are introduced, and research needs and future challenges are identifi ed. Land surface provides the lower boundary condition to the atmosphere over continents by controlling the fl uxes of momentum, heat, water, and materials such as carbon. In turn, land surface conditions are substantially infl uenced by atmospheric conditions on various temporal scales. As such, a land-atmosphere coupled system is established through biogeochemical feedbacks. Current land surface models exhibit a wide variety of responses to the same forcings, suggesting the need for increased research at the land-atmosphere interface. Indeed, all Earth System Models require the inclusion and validation of the processes that pertain to the biogeochemical feedbacks. Anthropogenic activities that result in land use and land cover changes affect the land surface characteristics and consequently the land-atmosphere feedbacks and coupling strength. Therefore, human activities play a role in the landatmosphere coupling system, and thus, in the climate system. Water is essential to societal needs that require the construction of reservoirs, extraction of ground water, irrigation, changes in land use, urbanization among many other infl uences. The extent and sustainability of those interferences in the natural system remains to be assessed at global scales.

Flow regime change in an endorheic basin in southern Ethiopia

“…LULC change such as the conversion of forest land to crop land resulted in an increase of flow due to reduction of evaporation and infiltration (Fissekis, 2007;Newson, 1997;Rost et al, 2008;Pikounis et al, 2003). Oki et al (2011) reach a similar conclusion on the impact of LULC change on precipitation, potential evaporation and streamflow by using a simple water balance based on the Budyko equations (Budyko, 1974).…”

On inclusion of water resource management in Earth system models – Part 1: Problem definition and representation of water demand

“…The terrestrial water cycle is one set of Earth system processes that is greatly perturbed by human activities; it also is of critical importance in determining human health, safety and livelihoods, as well as local, regional and global economies (e.g., Nilsson et al, 2005). However, although some anthropogenic effects, such as the emission of greenhouse gases and land-use change, have been incorporated in LSMs (e.g., Lenton, 2000;Zhao et al, 2001;Karl and Trenberth, 2003;Brovkin et al, 2006;Solomon et al, 2009), less effort has been made to represent human-water interactions (e.g., Trenberth and Asrar, 2012;Lawrence et al, 2012;Oki et al, 2013). This can be a major reason for current deficiencies in hydrological performance of large-scale modes (i.e., LSMs and/or GHMs).…”

On inclusion of water resource management in Earth system models – Part 2: Representation of water supply and allocation and opportunities for improved modeling

“…At this stage of research, major gaps are noted in spatial and temporal quality and coverage of the data related to climate, hydrology, socio-economy, policy and water resource management that are required to drive or to support large-scale models (see Wood et al, 2011;Gleick et al, 2013;Oki et al, 2013).…”

“…Similarly, estimates of inflows to reservoirs govern the calculations related to reservoir releases and storage. Currently, there are major limitations in representing soil moisture, snow cover, permafrost, evapotranspiration, deep percolation and runoff in large-scale models and they cannot be represented without large uncertainty Trenberth and Asrar, 2012;Oki et al, 2013). Moreover, host models often contain missing processes.…”

“…Some systematic frameworks for calibration and parameterization of land-surface processes are suggested (Rosolem et al, 2012(Rosolem et al, , 2013. We expect improvements in process representations and parameterizations related to LSMs will increase in near future due to the need that has been already recognized (e.g., Wood et al, 2011;Lawrence et al, 2012;Trenberth and Asrar, 2012;Gleick et al, 2013;Oki et al, 2013;Dadson et al, 2013).…”