scholarly journals Impact of Forest Cover Change on Available Water Resources: Long-Term Forest Cover Dynamics of the Semi-Arid Dhofar Cloud Forest, Oman

2020 ◽  
Vol 8 ◽  
Author(s):  
Romy Arnold ◽  
Jan-Karl Haug ◽  
Maximilian Lange ◽  
Jan Friesen
Keyword(s):  
Water Resources ◽  
Forest Cover ◽  
Cloud Forest ◽  
Forest Cover Change ◽  
Available Water ◽  
Semi Arid

scholarly journals Shedding New Light on Mountainous Forest Growth: A Cross-Scale Evaluation of the Effects of Topographic Illumination Correction on 25 Years of Forest Cover Change across Nepal

2021 ◽  
Vol 13 (11) ◽  
pp. 2131
Author(s):  
Jamon Van Den Hoek ◽  
Alexander C. Smith ◽  
Kaspar Hurni ◽  
Sumeet Saksena ◽  
Jefferson Fox
Keyword(s):  
Remote Sensing ◽  
Geographic Distribution ◽  
Classification Accuracy ◽  
Forest Cover ◽  
Forest Growth ◽  
Forest Cover Change ◽  
Scale Evaluation ◽  
Beneficial Effects ◽  
Affect Detection

Accurate remote sensing of mountainous forest cover change is important for myriad social and ecological reasons, but is challenged by topographic and illumination conditions that can affect detection of forests. Several topographic illumination correction (TIC) approaches have been developed to mitigate these effects, but existing research has focused mostly on whether TIC improves forest cover classification accuracy and has usually found only marginal gains. However, the beneficial effects of TIC may go well beyond accuracy since TIC promises to improve detection of low illuminated forest cover and thereby normalize measurements of the amount, geographic distribution, and rate of forest cover change regardless of illumination. To assess the effects of TIC on the extent and geographic distribution of forest cover change, in addition to classification accuracy, we mapped forest cover across mountainous Nepal using a 25-year (1992–2016) gap-filled Landsat time series in two ways—with and without TIC (i.e., nonTIC)—and classified annual forest cover using a Random Forest classifier. We found that TIC modestly increased classifier accuracy and produced more conservative estimates of net forest cover change across Nepal (−5.2% from 1992–2016) TIC. TIC also resulted in a more even distribution of forest cover gain across Nepal with 3–5% more net gain and 4–6% more regenerated forest in the least illuminated regions. These results show that TIC helped to normalize forest cover change across varying illumination conditions with particular benefits for detecting mountainous forest cover gain. We encourage the use of TIC for satellite remote sensing detection of long-term mountainous forest cover change.

scholarly journals Uncertainty in Historical Land-Use Reconstructions with Topographic Maps

2014 ◽  
Vol 33 (3) ◽  
pp. 55-63 ◽  
Author(s):  
Dominik Kaim ◽  
Jacek Kozak ◽  
Krzysztof Ostafin ◽  
Monika Dobosz ◽  
Katarzyna Ostapowicz ◽  
...  
Keyword(s):  
Land Use ◽  
Forest Cover ◽  
Reliability Assessment ◽  
Swiss Alps ◽  
Topographic Maps ◽  
Forest Cover Change ◽  
Change Analysis ◽  
Polish Carpathians ◽  
Historical Land Use

Abstract The paper presents the outcomes of the uncertainty investigation of a long-term forest cover change analysis in the Polish Carpathians (nearly 20,000 km2) and Swiss Alps (nearly 10,000 km2) based on topographic maps. Following Leyk et al. (2005) all possible uncertainties are grouped into three domains - production-oriented, transformation- oriented and application-oriented. We show typical examples for each uncertainty domain, encountered during the forest cover change analysis and discuss consequences for change detection. Finally, a proposal for reliability assessment is presented.

scholarly journals Evaluation of regional droughts using monthly gridded precipitation for Korea

2012 ◽  
Vol 14 (4) ◽  
pp. 1036-1050 ◽  
Author(s):  
Syed Zakir Hossein ◽  
Han Man Shin ◽  
Choi Gyewoon
Keyword(s):  
Water Resources ◽  
Kriging Interpolation ◽  
Drought Severity ◽  
Drought Risk ◽  
Data Sets ◽  
Monthly Precipitation ◽  
Gridded Data ◽  
Data Set ◽  
Available Water

This paper attempts to characterize regional drought using 0.5 degree reanalyzed GPCC (Global Precipitation Climatology Center) gauge-based gridded monthly precipitation data sets in Korea. Drought is a function of precipitation and long-term observed precipitation was performed to enhance this characterization. There are limited long-term records from each station, therefore, a global gridded data set has been employed. Before using this data, 10 corresponding grids with KMA (Korea Meteorology Administration) stations were validated through cross-correlations (0.93–0.99). The impacts of drought are dependent on its duration, severity and spatial extent. Drought occurs when a below average water availability persists and becomes regionally extensive. In this study, 66 GPCC gridded precipitations were employed to estimate the effective drought index along with the available water resource index. The results of the 10 KMA corresponding stations were as accurate as those of the global data. Consequently, gridded data are suitable for a monthly drought severity investigation. In addition, spatial distribution of drought and available water resources were exposed by kriging interpolation technique over Korea. Through this study, drought risk city Taebaek in Kangwon province was classified by its 2009 intensity of monthly precipitations, droughts and available water resources.

scholarly journals Temporal trend of drought and aridity indices in semi-arid pernambucano to determine susceptibility to desertification

RBRH ◽  
2020 ◽  
Vol 25 ◽  
Author(s):  
Fabianny Joanny Bezerra Cabral da Silva ◽  
José Roberto Gonçalves de Azevedo
Keyword(s):  
Water Resources ◽  
Water Resources Management ◽  
Extreme Events ◽  
Climate Trend ◽  
Resources Management ◽  
Tukey Test ◽  
Hydrological Extreme ◽  
Aridity Indices ◽  
Semi Arid

ABSTRACT In semi-arid regions, the use of drought and aridity indices in order to establish diagnoses and prognoses that help in water resources management is crucial, above all, for the evaluation of long-term water availability, and monitoring hydrological extreme events. Therefore, the aim of this study was to evaluate the trends of extreme events to determine susceptibility to desertification in the Brígida river basin, by Drought (RAI, SPI and PDSI) and Aridity (MIA, AI and AIASD) Indices. The results of these indices submitted to statistical analysis (Tukey Test) and to the evaluation of the climate trend (TREND software). The Tukey Test indicated that the PDSI and RAI method are the most suitable for drought analysis, while AI is most appropriate for aridity. The results indicated that regardless of the indices employed, the stations presented significant results in the trend analysis, suggesting intensification of these events over time. Therefore, concluded that drought and aridity indices could help water resources management by managing bodies, indicating the evolution of extreme hydrological phenomena, suggesting the adoption of preventive and mitigating actions regarding the use of water priority. In conclusion, these indices can be used as a tool for indicating areas susceptible to the desertification process.

scholarly journals Global-scale modeling of groundwater recharge

2008 ◽  
Vol 12 (3) ◽  
pp. 863-885 ◽  
Author(s):  
P. Döll ◽  
K. Fiedler
Keyword(s):  
Water Resources ◽  
Groundwater Recharge ◽  
Arid Regions ◽  
Groundwater Resources ◽  
Global Scale ◽  
Unbiased Estimation ◽  
Data Sets ◽  
Total Runoff ◽  
Semi Arid

Abstract. Long-term average groundwater recharge, which is equivalent to renewable groundwater resources, is the major limiting factor for the sustainable use of groundwater. Compared to surface water resources, groundwater resources are more protected from pollution, and their use is less restricted by seasonal and inter-annual flow variations. To support water management in a globalized world, it is necessary to estimate groundwater recharge at the global scale. Here, we present a best estimate of global-scale long-term average diffuse groundwater recharge (i.e. renewable groundwater resources) that has been calculated by the most recent version of the WaterGAP Global Hydrology Model WGHM (spatial resolution of 0.5° by 0.5°, daily time steps). The estimate was obtained using two state-of-the-art global data sets of gridded observed precipitation that we corrected for measurement errors, which also allowed to quantify the uncertainty due to these equally uncertain data sets. The standard WGHM groundwater recharge algorithm was modified for semi-arid and arid regions, based on independent estimates of diffuse groundwater recharge, which lead to an unbiased estimation of groundwater recharge in these regions. WGHM was tuned against observed long-term average river discharge at 1235 gauging stations by adjusting, individually for each basin, the partitioning of precipitation into evapotranspiration and total runoff. We estimate that global groundwater recharge was 12 666 km3/yr for the climate normal 1961–1990, i.e. 32% of total renewable water resources. In semi-arid and arid regions, mountainous regions, permafrost regions and in the Asian Monsoon region, groundwater recharge accounts for a lower fraction of total runoff, which makes these regions particularly vulnerable to seasonal and inter-annual precipitation variability and water pollution. Average per-capita renewable groundwater resources of countries vary between 8 m3/(capita yr) for Egypt to more than 1 million m3/(capita yr) for the Falkland Islands, the global average in the year 2000 being 2091 m3/(capita yr). Regarding the uncertainty of estimated groundwater resources due to the two precipitation data sets, deviation from the mean is 1.1% for the global value, and less than 1% for 50 out of the 165 countries considered, between 1 and 5% for 62, between 5 and 20% for 43 and between 20 and 80% for 10 countries. Deviations at the grid scale can be much larger, ranging between 0 and 186 mm/yr.

scholarly journals Global-scale modeling of groundwater recharge

2007 ◽  
Vol 4 (6) ◽  
pp. 4069-4124 ◽  
Author(s):  
P. Döll ◽  
K. Fiedler
Keyword(s):  
Water Resources ◽  
Groundwater Recharge ◽  
Arid Regions ◽  
Groundwater Resources ◽  
Global Scale ◽  
Unbiased Estimation ◽  
Data Sets ◽  
Total Runoff ◽  
Semi Arid

Abstract. Long-term average groundwater recharge, which is equivalent to renewable groundwater resources, is the major limiting factor for the sustainable use of groundwater. Compared to surface water resources, groundwater resources are more protected from pollution, and their use is less restricted by seasonal and inter-annual flow variations. To support water management in a globalized world, it is necessary to estimate groundwater recharge at the global scale. Here, we present a best estimate of global-scale long-term average diffuse groundwater recharge (i.e. renewable groundwater resources) that has been calculated by the most recent version of the WaterGAP Global Hydrology Model WGHM (spatial resolution of 0.5° by 0.5°, daily time steps). The estimate was obtained using two state-of-the art global data sets of gridded observed precipitation that we corrected for measurement errors, which also allowed to quantify the uncertainty due to these equally uncertain data sets. The standard WGHM groundwater recharge algorithm was modified for semi-arid and arid regions, based on independent estimates of diffuse groundwater recharge, which lead to an unbiased estimation of groundwater recharge in these regions. WGHM was tuned against observed long-term average river discharge at 1235 gauging stations by adjusting, individually for each basin, the partitioning of precipitation into evapotranspiration and total runoff. We estimate that global groundwater recharge was 12 666 km3/yr for the climate normal 1961–1990, i.e. 32% of total renewable water resources. In semi-arid and arid regions, mountainous regions, permafrost regions and in the Asian Monsoon region, groundwater recharge accounts for a lower fraction of total runoff, which makes these regions particularly vulnerable to seasonal and inter-annual precipitation variability and water pollution. Average per-capita renewable groundwater resources of countries vary between 8 m3/(capita yr) for Egypt to more than 1 million m3/(capita yr) for the Falkland Islands, the global average in the year 2000 being 2091 m3/(capita yr). Regarding the uncertainty of estimated groundwater resources due to the two precipitation data sets, deviation from the mean is less than 1% for 50 out of the 165 countries considered, between 1 and 5% for 62, between 5 and 20% for 43 and between 20 and 80% for 10 countries. Deviations at the grid scale can be much larger, ranging between 0 and 186 mm/yr.

Satellite time series analysis of vegetation dynamics for water resources management in semi-arid regions

2020 ◽  
Author(s):  
Robert Behling ◽  
Sigrid Roessner ◽  
Saskia Foerster
Keyword(s):  
Water Management ◽  
Land Use ◽  
Time Series ◽  
Water Resources ◽  
Water Resources Management ◽  
Vegetation Dynamics ◽  
Arid Regions ◽  
Resources Management ◽  
Semi Arid

<p>One of the consequences of global climate change is the more frequent occurrence of extreme weather conditions. Semi-arid regions are especially vulnerable since evapotranspiration significantly exceeds precipitation for most of the year and rainfall occurrence is dominantly sporadic and highly variable in amount and spatial extent. Consequently, these regions suffer from droughts of increasing duration and severity, occasionally interrupted by strong rainfall events generating high surface runoff and in part highly destructive floods. In semi-arid regions water retention capability is often further reduced by changes of the original vegetation cover due to conversion into farmland and intensification of land use. The result is widespread land degradation by a decrease in permanent vegetation cover and an increase in soil erosion. Under such conditions sustainable water resources management is of key importance, however, reliable long-term observations describing the water cycle and the resulting water budget are missing for many regions of the world. This situation requires new approaches in improving seasonal forecast for relevant water resources parameters as well as spatiotemporally explicit understanding the of influence of water and land use management on the long-term development of water availability and land surface conditions. <br>The German collaborative research project ‘Seasonal water resources management in semi-arid regions: Transfer of regionalized global information to practice’ (SaWaM) aims at the development of methods allowing the use of global data for deriving information needed for regional water resources management in semi-arid regions by integrating meteorological, hydrological and ecosystem sciences and supported by satellite remote sensing analysis. The performance, practical applicability and transferability of the developed methods are assessed in several semi-arid regions including Brazil, Iran and Sudan. Here, we present our work on the analysis of the seasonal and long-term vegetation dynamics at different spatial and temporal scales using satellite time series data of different spatial and temporal resolution (MODIS and Sentinel-2).  Our goal is linking the derived vegetation dynamics to changes in meteorological conditions, water availability and land use. In this context we put emphasis on the spatiotemporal analysis of bioproductivity related to different land use types and climatic conditions to identify and characterize hotspots of water usage in form of irrigated agriculture as a basis for further evaluation of the underlying water management practices.<br>We perform time series analysis of satellite-derived vegetation indices (VI) using various statistical aggregates, such as maximum, mean and temporal duration related to variable time periods (hydrological year, dry and wet season, growing patterns) as well as additive time series decomposition. Thus, we analyze long-term trends, seasonal deviations from long-term average conditions, and break points in the time series related to land use and water management changes. Moreover, we compare the derived spatiotemporal VI dynamics against the dynamics of hydrometeorological conditions (e.g. precipitation, evapotranspiration, temperature) as well as land use patterns in order to evaluate the impact of hydrometeorological drought conditions on different land use types and water management practices.  In conclusion, we present prototypes for information products supporting decision making of the local experts in the target regions.</p>

The deforestation-income relationship: evidence of deforestation convergence across developing countries

2020 ◽  
pp. 1-20
Author(s):  
Boka Stéphane Kévin Assa
Keyword(s):  
Developing Countries ◽  
Forest Conservation ◽  
Forest Cover ◽  
Forest Degradation ◽  
Forest Transition ◽  
Forest Cover Change ◽  
Recent Method ◽  
Per Capita ◽  
Beta Convergence

Abstract The importance of forest conservation in the fight against emissions from deforestation and forest degradation has led to reexamination of the deforestation and economic development relationship. For this purpose, we use the recent method of long-term growth rate developed by Stern et al. (2017) on 85 tropical developing countries over the period 1990–2010. Results show that the EKC is not significant. However, we find a beta convergence across developing countries in terms of deforestation per capita. In other words, these countries converge in terms of policies that prevent deforestation and forest degradation. This implies that, just as with growth effects, beta convergence effects are also important in explaining changes in forest cover in tropical developing countries. The convergence effect in forest cover change may be consistent with the forest transition hypothesis.

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