scholarly journals Modeling the Effects of Anthropogenic Land Cover Changes to the Main Hydrometeorological Factors in a Regional Watershed, Central Greece

Climate ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 129 ◽  
Author(s):  
Angeliki Mentzafou ◽  
George Varlas ◽  
Elias Dimitriou ◽  
Anastasios Papadopoulos ◽  
Ioannis Pytharoulis ◽  
...  

In this study, the physically-based hydrological model MIKE SHE was employed to investigate the effects of anthropogenic land cover changes to the hydrological cycle components of a regional watershed in Central Greece. Three case studies based on the land cover of the years 1960, 1990, and 2018 were examined. Copernicus Climate Change Service E-OBS gridded meteorological data for 45 hydrological years were used as forcing for the model. Evaluation against observational data yielded sufficient quality for daily air temperature and precipitation. Simulation results demonstrated that the climatic variabilities primarily in precipitation and secondarily in air temperature affected basin-averaged annual actual evapotranspiration and average annual river discharge. Nevertheless, land cover effects can locally outflank the impact of climatic variability as indicated by the low interannual variabilities of differences in annual actual evapotranspiration among case studies. The transition from forest to pastures or agricultural land reduced annual actual evapotranspiration and increased average annual river discharge while intensifying the vulnerability to hydrometeorological-related hazards such as droughts or floods. Hence, the quantitative assessment of land cover effects presented in this study can contribute to the design and implementation of successful land cover and climate change mitigation and adaptation policies.

2021 ◽  
Author(s):  
Julie Collignan ◽  
Jan Polcher ◽  
Pere Quintana Seguí

<p>In a context of climate change, the stakes surrounding water availability and use are getting higher, especially in semi-arid climates. Human activities such as irrigation and land cover changes impact the water cycle, raising questions around the effects it could have on regional atmospheric circulation and how to separate the impact of climate change from the impact of anthropogenic activities to better understand their role in the historical records. The ORCHIDEE Land Surface Model from Institut Pierre Simon Laplace (IPSL) simulates global carbon cycle and aims at quantifying terrestrial water and energy balance. It is being developed at regional scale but does not include satisfying hypothesis to account for human activities such as irrigation at such scale so far.</p><p>We <span>propose</span> a methodology to semi-empirically separate the effect of climate from the impact of the changing catchment characteristics on river discharge. <span>It is based on</span> the Budyko framework and <span>allows to characterise the</span> annual river discharge of over 363 river monitoring stations in Spain. The Budyko parameter is estimated for each basin and <span>represents</span> its hydrological characteristics. Precipitations and potential evapotranspiration are derived from the forcing dataset GSWP3 (Global Soil Wetness Project Phase 3) – from 1901 to 2010 –. Two methods are used to estimate evapotranspiration : the first uses evapotranspiration from the ORCHIDEE LSM outputs while the second deduced evapotranspiration from river discharge observations and the water balance equation. The first method only accounts for the effects of atmospheric forcing while the other combines, through the observations, <span>climatic and non-climatic processes</span> over the watersheds. We then study the evolution over the <span>Budyko</span> parameter fitted with these two <span>estimates of evaporation</span>. Studying the watershed parameter allows us to free ourselves from some of the climate interannual variability compared to directly looking at changes in the river discharge and better separate anthropogenic changes from the effect of climatic forcing.</p><p>Our results show that for most basins tested over Spain, there is an increasing trend in the <span>Budyko parameter representing increasing evaporation efficiency</span> of the watershed which <span>can not be</span> explained by the climate forcing. This trend is consistent with changes in irrigation equipment and land cover changes over the studied period. However changes of the basin characteristics can not be fully quantified by this variables. Other factors as glaciers melting which derails the water balance over our time of study.</p><p>The methodology needs to be extended to other areas such as Northern Europe to see if the differences in response of the catchments to anthropogenic changes quantified by our methodology corresponds to known contrasts. Balance between climatic and anthropogenic changes of basin characteristics are different in semi-arid climate than in northern more humid regions.</p>


2021 ◽  
Vol 325 ◽  
pp. 08010
Author(s):  
Gita Ivana Suci Lestari Faski ◽  
Ignasius Loyola Setyawan Purnama

Global climate change that occurred in this century can affect the pattern of rain and increase in temperature on earth. This study aims to determine and analyze the increase in rainfall, air temperature, potential evapotranspiration and actual evapotranspiration in the Bengkulu watershed. For this reason, the regional rainfall is calculated using the Thiessen Polygon, the mean air temperature of the watershed based on the median elevation, potential evapotranspiration using the Thornthwaite Method and actual evapotranspiration using the basis of the difference in rainfall to potential evapotranspiration. The results showed that every year there was an increase in rainfall, air temperature, potential evapotranspiration and actual evapotranspiration in the Bengkulu Watershed. In the 2009-2013 period, the average annual rainfall of 3,581 mm increased to 3,641 mm in the 2014-2018 period. For air temperature, the average monthly air temperature in the Bengkulu Watershed for the 2009-2013 period was 25.8°C, while the air temperature in the 2014-2018 period was 26.1°C. This means that in a period of 5 years there is an increase in temperature of 0.3°C. Furthermore, due to the increase in air temperature, there was an increase in the average monthly potential evapotranspiration from the 2009-2013 period to the 2014-2018 period, namely from 1,493 mm to 1,537 mm, while for actual evapotranspiration there was an increase from 1,486 mm to 1,518 mm.


2021 ◽  
Vol 12 (2) ◽  
pp. 635-670
Author(s):  
Wolfgang A. Obermeier ◽  
Julia E. M. S. Nabel ◽  
Tammas Loughran ◽  
Kerstin Hartung ◽  
Ana Bastos ◽  
...  

Abstract. Quantifying the net carbon flux from land use and land cover changes (fLULCC) is critical for understanding the global carbon cycle and, hence, to support climate change mitigation. However, large-scale fLULCC is not directly measurable and has to be inferred from models instead, such as semi-empirical bookkeeping models and process-based dynamic global vegetation models (DGVMs). By definition, fLULCC estimates are not directly comparable between these two different model types. As an important example, DGVM-based fLULCC in the annual global carbon budgets is estimated under transient environmental forcing and includes the so-called loss of additional sink capacity (LASC). The LASC results from the impact of environmental changes on land carbon storage potential of managed land compared to potential vegetation and accumulates over time, which is not captured in bookkeeping models. The fLULCC from transient DGVM simulations, thus, strongly depends on the timing of land use and land cover changes mainly because LASC accumulation is cut off at the end of the simulated period. To estimate the LASC, the fLULCC from pre-industrial DGVM simulations, which is independent of changing environmental conditions, can be used. Additionally, DGVMs using constant present-day environmental forcing enable an approximation of bookkeeping estimates. Here, we analyse these three DGVM-derived fLULCC estimations (under transient, pre-industrial, and present-day forcing) for 12 models within 18 regions and quantify their differences as well as climate- and CO2-induced components and compare them to bookkeeping estimates. Averaged across the models, we find a global fLULCC (under transient conditions) of 2.0±0.6 PgC yr−1 for 2009–2018, of which ∼40 % are attributable to the LASC (0.8±0.3 PgC yr−1). From 1850 onward, the fLULCC accumulated to 189±56 PgC with 40±15 PgC from the LASC. Around 1960, the accumulating nature of the LASC causes global transient fLULCC estimates to exceed estimates under present-day conditions, despite generally increased carbon stocks in the latter. Regional hotspots of high cumulative and annual LASC values are found in the USA, China, Brazil, equatorial Africa, and Southeast Asia, mainly due to deforestation for cropland. Distinct negative LASC estimates in Europe (early reforestation) and from 2000 onward in the Ukraine (recultivation of post-Soviet abandoned agricultural land), indicate that fLULCC estimates in these regions are lower in transient DGVM compared to bookkeeping approaches. Our study unravels the strong dependence of fLULCC estimates on the time a certain land use and land cover change event happened to occur and on the chosen time period for the forcing of environmental conditions in the underlying simulations. We argue for an approach that provides an accounting of the fLULCC that is more robust against these choices, for example by estimating a mean DGVM ensemble fLULCC and LASC for a defined reference period and homogeneous environmental changes (CO2 only).


2021 ◽  
Vol 13 (3) ◽  
pp. 1153
Author(s):  
Batsuren Dorjsuren ◽  
Nyamdavaa Batsaikhan ◽  
Denghua Yan ◽  
Otgonbayar Yadamjav ◽  
Sonomdagva Chonokhuu ◽  
...  

The Tuul River Basin is the most important socioeconomic and political base area of Mongolia. Therefore, studying the interrelationships between changes in the ecohydrological processes of this basin and its land cover is of great importance for maintaining sustainability and the environment. This study investigated the annual average air temperature, total annual precipitation, and river discharge variability, and land cover changes at selected stations of the basin by using the hydrometeorological analysis, satellite analysis, and land cover determination statistical analysis. During the study period, the average annual air temperature rose from −1.5 °C to +0.3 °C (1.8 °C 361 °C). The average annual precipitation exhibits relatively low change during this period. River discharge varied during the study period. A significant decreasing trend in river discharge was observed at the Terelj (φ = −2.72) and Ulaanbaatar (φ = −5.63) stations, whereas the other stations, Altanbulag, Lun, and Orkhontuul, showed a significant increasing trend. During the study period, changes in land cover were directly related to main hydrometeorological parameters. Between 2000 and 2020, the amount of grassland decreased by 319.67 km2, while the area of water bodies increased by 28.36 km2. In the study area, mainly water bodies and sensitive areas of the land cover types were changed due to changes in precipitation. Studies in the arid and semiarid regions of Central Asia show that changes of ecohydrological processes have a significant impact on land cover changes.


2018 ◽  
Author(s):  
Poerbandono ◽  
Miga Magenika Julian ◽  
Philip J. Ward

In Jakarta, climate change has been detected through rising air temperatures, increased intensity of rainfall in the wet season, and sea level rise. The coupling of such changes with local anthropogenic driven modifications in the environmental setting could contribute to an increased probability of flooding, due to increase in both extreme river discharge and sedimentation (as a result of erosion in the watersheds above Jakarta and as indicated by sediment yield in the downstream area). In order to respond to the observed and projected changes in river discharge and sediment yield, and their secondary impacts, adaptation strategies are required. A possible adaptation strategy is through policy making in the field of spatial planning. For example, in Indonesia, presidential regulation number 54 year 2008 (Peraturan Presiden Nomor 54 Tahun 2008—Perpres 54/2008) was issued as a reference for the implementation of water and soil conservation. This paper assesses the impact of climate and land cover change on river discharge and sediment yield, as well as the effects of Perpres 54/2008 on that river discharge and sediment yield. The spatial water balance model Spatial Tools for River Basins and Environmental and Analysis of Management Option was used for the runoff computations, whilst the Spatial Decision Assistance of Watershed Sedimentation model was used to simulate erosion, Sediment Delivery Ratio, and sediment yield. The computation period is from January 1901 to December 2005, at the scale of the following watersheds: Ciujung, Cisadane, Ciliwung, and Citarum. During the twentieth century, computed average discharge in the downstream area (near Jakarta) increased between 2.5 and 35 m³/s/month, and sediment yield increased between 1 x 10² and 42 x 10³ tons/year. These changes were caused by changes in both land cover and climate, with the former playing a stronger role. Based on a computation under a theoretical full implementation of the spatial plan proposed by Perpres 54/2008, river discharge would decrease by up to 5 % in the Ciliwung watershed and 26 % in the Cisadane watershed. The implementation of Perpres 54/2008 could also decrease the sediment yield, by up to 61 and 22 % in the Ciliwung and Cisadane watersheds, respectively. These findings show that the implementation of the spatial plan of Perpres 54/2008 could significantly improve watershed response to runoff and erosion. This study may serve as a tool for assessing the reduction in climate change impacts and evaluating the role of spatial planning for adaptation strategies.


2021 ◽  
Author(s):  
Wolfgang A. Obermeier ◽  
Julia E. M. S. Nabel ◽  
Tammas Loughran ◽  
Kerstin Hartung ◽  
Ana Bastos ◽  
...  

Abstract. Quantifying the net carbon flux from land use and land cover changes (fLULCC) is critical for understanding the global carbon cycle, and hence, to support climate change mitigation. However, large-scale fLULCC is not directly measurable, but has to be inferred from models instead, such as semi-empirical bookkeeping models, and process-based dynamic global vegetation models (DGVMs). By definition, fLULCC estimates are not directly comparable between these two different model types. As an example, DGVM-based fLULCC in the annual global carbon budgets is estimated under transient environmental forcing and includes the so-called Loss of Additional Sink Capacity (LASC). The LASC accounts for the impact of environmental changes on land carbon storage potential of managed land compared to potential vegetation which is not represented in bookkeeping models. In addition, fLULCC from transient DGVM simulations differs depending on the arbitrary chosen simulation time period and the historical timing of land use and land cover changes (including different accumulation periods for legacy effects). An approximation of fLULCC by DGVMs that is independent of the timing of land use and land cover changes and their legacy effects requires simulations assuming constant pre-industrial or present-day environmental forcings. Here, we analyze three DGVM-derived fLULCC estimations for twelve models within 18 regions and quantify their differences as well as climate- and CO2-induced components. The three estimations stem from the commonly performed simulation with transiently changing environmental conditions and two simulations that keep environmental conditions fixed, at pre-industrial and present-day conditions. Averaged across the models, we find a global fLULCC (under transient conditions) of 2.0 ± 0.6 PgC yr-1 for 2009–2018, of which ∼40 % are attributable to the LASC (0.8 ± 0.3 PgC yr-1). From 1850 onward, fLULCC accumulated to 189 ± 56 PgC with 40 ± 15 PgC from the LASC. Regional hotspots of high cumulative and annual LASC values are found in the USA, China, Brazil, Equatorial Africa and Southeast Asia, mainly due to deforestation for cropland. Distinct negative LASC estimates, in Europe (early reforestation) and from 2000 onward in the Ukraine (recultivation of post-Soviet abandoned agricultural land), indicate that fLULCC estimates in these regions are lower in transient DGVM- compared to bookkeeping-approaches. By unraveling spatio-temporal variability in three alternative DGVM-derived fLULCC estimates, our results call for a harmonized attribution of model-derived fLULCC. We propose an approach that bridges bookkeeping and DGVM approaches for fLULCC estimation by adopting a mean DGVM-ensemble LASC for a defined reference period.


2015 ◽  
Vol 15 (13) ◽  
pp. 18459-18485
Author(s):  
T. Verbeke ◽  
J. Lathière ◽  
S. Szopa ◽  
N. de Noblet-Ducoudré

Abstract. Dry deposition is a key component of surface–atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries, and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between present-day (2006) and the future (2050) on dry deposition rates, with special interest for ozone (O3) and nitric acid vapor (HNO3), two compounds which are characterized by very different physico-chemical properties. The 3-D chemistry transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections RCPs 2.6, 4.5 and 8.5. The 2050 RCP 8.5 vegetation distribution leads to a rise up to 7 % (+0.02 cm s−1) in VdO3 and a decrease of −0.06 cm s−1 in VdHNO3 relative to the present day values in tropical Africa, and up to +18 and −15 % respectively in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land cover change in Eurasia, VdHNO3 increases by up to 20 % (annual-mean value) and reduces VdO3 by the same magnitude in this region. When analyzing the impact of dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual mean surface ozone concentration, for both for the RCP8.5 and RCP2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios, regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a significant increase of the surface O3 concentration reaching locally up to 5 ppb (+5 %) is calculated on average during the June–August period. This scenario induces also an increase of HNO3 deposited flux exceeding locally 10 % for monthly values. Comparing the impact of land-cover change to the impact of climate change, considering a 0.93 °C increase of global temperature, on dry deposition velocities, we estimate that the strongest increase over lands occurs in the North Hemisphere during winter especially in Eurasia, by +50 % (+0.07 cm s−1) for VdO3 and +100 % (+0.9 cm s−1) for VdHNO3. However, different regions are affected by both changes, with climate change impact on deposition characterized by a latitudinal gradient, while the land-cover change impact is much more heterogeneous depending on vegetation distribution modification described in the future RCP scenarios. The impact of long-term land-cover changes on dry deposition is shown to be non-negligible and should be therefore considered in biosphere-atmospheric chemistry interaction studies in order to have a fully consistent picture.


Degradation currently affects 25 % of the land on Earth and 40 % of the agricultural land on Earth. Environmental effects of soil degradation are widespread, including increased soil losses, deterioration of water quality, decline of biodiversity and degradation of ecological resources and associated values, especially where actual land use is disrespectful (natural use in circumstances where land is in conflict with the environment. Changes in temperature, wind velocity, and precipitation patterns can affect the production of plant biomass, land use, land cover, soil moisture, infiltration rate, runoff and crop management, and eventually land degradation. In recent decades, powerful partnerships have been seen between global climate change and land loss processes. In order to reliably define or forecast the effect of climate change on the loss of land, models of climate change and land use models should be combined with hydrology. Until the first seventies land degradation and geological process weren't thought of a serious issue in most Mediterranean regions. Traditional agricultural systems were believed to be able to keep those processes under control. So low priority was appointed to research programmes and comes on eroding and conservation, preference being given to the impact of farm machinery on soil structure and compaction beside the role of organic matter within the soil. To regulate the destruction of soil, it is therefore important to have limited and global strategies and regulations. Land use and land cover changes influence carbon fluxes and GHGs emissions that directly alter atmospherical composition and radioactive forcing properties. Land degradation aggravates greenhouse gas-induced global climate change through the discharge of CO2 from cleared and dead vegetation and thru the reduction of the carbon sequestration potential of degraded land. The present analysis furnishes effects of climate amendment on land degradation.


2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Xiangzheng Deng ◽  
Chunhong Zhao ◽  
Haiming Yan

There have been tremendous changes in the global land use pattern in the past 50 years, which has directly or indirectly exerted significant influence on the global climate change. Quantitative analysis for the impacts of land use and land cover changes (LUCC) on surface climate is one of the core scientific issues to quantitatively analyze the impacts of LUCC on the climate so as to scientifically understand the influence of human activities on the climate change. This paper comprehensively analyzed the primary scientific issues about the impacts of LUCC on the regional climate and reviewed the progress in relevant researches. Firstly, it introduced the influence mechanism of LUCC on the regional climate and reviewed the progress in the researches on the biogeophysical process and biogeochemical process. Then the model simulation of effects of LUCC on the regional climate was introduced, and the development from the global climate model to the regional climate model and the integration of the improved land surface model and the regional climate model were reviewed in detail. Finally, this paper discussed the application of the regional climate models in the development and management of agricultural land and urban land.


2021 ◽  
Author(s):  
Hadi Eskandari Damaneh ◽  
Hassan Khosravi ◽  
Khalil Habashi ◽  
Hamed Eskandari Damaneh ◽  
John P. Tiefenbacher

Abstract Estimates of long-term change and land cover changes using satellite imagery update data about effects erosion on the destruction. This is relevant on semi-arid land where soil resources are scarce, and proper management requires matching LULC to the conditions to achieve sustainability. This study evaluates the impact of LULC changes on soil erosion using Landsat satellite images and the RUSLE model on plains around the Jarahi River and Shadegan International Wetlands. The maps of LULC were prepared with supervised classification and maximum-likelihood methods applied to pre-processed TM, ETM, and OLI images for 1989, 2003, and 2017. This study investigated the impacts of LULC changes on soil erosion. Based on the results, we observe that an assessment of LULC changes from 1989 to 2003 revealed diminishing bare land and wetland vegetation with increases in agricultural land and water features. The areas of agricultural lands and wetlands decreased from 2003 to 2017, while bare lands increased in the area. The areas with soil erosion rates < 1 Mg ha-1 y-1 have diminished, and areas having rates >1 Mg ha-1 y-1 increased in extent. We conclude that LULC changes led to increased soil erosion in Shadegan International Wetlands. Our study highlights the need to plan LULC changes to reduce soil erosion rates to achieve sustainable management. We argue that nature-based solutions can effectively reduce soil losses.


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