Während sich die Siedlungs- und Verkehrsfläche in Deutschland weiterhin ausdehnt, ergeben sich neue Anforderungen an den Raum, die in gesteigerten Flächenkonkurrenzen und in der Verschärfung bestehender Umweltrisiken resultieren. Neben einer stärkeren Berücksichtigung von Klimaschutz und Energiewende bei der Entwicklung der Siedlungsstruktur wird ihre Anpassung an den Klimawandel gefordert, um negative Auswirkungen auf Bevölkerung, Wirtschaft und Infrastruktur abzuwenden. Im Rahmen des Forschungsprojektes CC-LandStraD („Climate Change – Land Use Strategies“) werden Wechselwirkungen zwischen der Landnutzung und dem Klimawandel für alle relevanten Landnutzungssektoren untersucht. Hierfür werden Landnutzungsänderungen in Deutschland bis zum Jahr 2030 simuliert und dabei ausgehend von einem Referenzszenario unterschiedliche Maßnahmen zum Klimaschutz und zur Anpassung an den Klimawandel implementiert. Die Wirksamkeit der Maßnahmen kann mithilfe von Indikatoren abgeschätzt werden. Es zeigt sich, dass sich die Flächenkonkurrenzen in einigen Regionen aufgrund der stärkeren Berücksichtigung von Klimaschutz und Klimaanpassung in der Siedlungsflächenentwicklung verschärfen werden. Betroffen sind vor allem die Regionen, die bereits heute entweder eine hohe Siedlungsdynamik aufweisen oder unter einem gewissen Anpassungsdruck (z. B. hinsichtlich Maßnahmen zum Hochwasserschutz) stehen.

Climate change and land use transition are the main drivers of watershed hydrological processes. The main objective of this study was to assess the hydrometeorological responses to climate and land use changes in the Jhelum River Basin (JRB), Pakistan. The development of proper climate information is a challenging task. To date, Global Climate Models (GCMs) are used for climate projections. However, these models have a coarse spatial resolution, which is not suitable for regional/local impact studies such as water resources management in the JRB. Therefore, different downscaling methods and techniques have been developed as means of bridging the gap between the coarse resolution global models projection and the spatial resolution required for hydrological impact studies. Statistical Downscaling Model (SDSM) and Long Ashton Research Station Weather Generator (LARS-WG) are selected in this study for downscaling of temperature and precipitation. Both downscaling approaches consider three climate models and two emission scenarios (i.e., RCP4.5 and RCP8.5) in order to sample the widest range of uncertainties in climate projections. Current land use and land cover (LULC) maps are generated from Landsat imagery to analyze the pattern and dynamic of land use change. Both climate projections and LULC are fed into SWAT (Soil and Water Assessment Tool) hydrological model to investigate the streamflow dynamics. The results indicate good applicability of SDSM and LARS-WG for downscaling of temperature and precipitation in three future periods (2020s, 2050s and 2080s). Both models show an increase mean annual max temperature, min temperature and precipitation as 0.4-4.2°C, 0.3-4.2°C and 4.4-32.2% under both RCPs scenarios. Similarly, results of SWAT model suggest an increase in mean annual discharge about 3.6 to 28.8% under RCP4.5 and RCP8.5. The study also revealed that water yield and evapotranspiration in the eastern part of the basin (sub-basins at high elevation) would be most affected by climate change. The results of LULC change detection show that forest exhibited maximum positive change while agriculture showed maximum negative change during 2001-2018. SWAT model simulations suggested that implementation of afforestation in the watershed would reduce surface runoff and water yield while enhancing the evapotranspiration. It is recommended that authorities should pay attention to both climate change and land use transition for proper water resources management.

The irrigated agriculture in the Lower Chenab Canal (LCC) of Pakistan is characterized by huge water utilization both from surface and groundwater resources. Need of utilization of water from five rivers in Punjab province along with accelerated population growth has forced the construction of world’s largest irrigation network. Nevertheless, huge irrigation infrastructure, together with inappropriate drainage infrastructure, led to a build-up of shal-low groundwater levels, followed by waterlogging and secondary salinization in the soil profile. Following this era, decreased efficiency of irrigation supply system along with higher food demands had increased burdens on groundwater use, which led to a drop in groundwater levels in major parts of LCC. Previous studies in the study region revealed lacking management and maintenance of irrigation system, inflexible irrigation strategies, poor linkages between field level water supply and demands. No future strategy is present or under consideration to deal with this long time emerged groundwater situation particularly under unchanged irrigation water supply and climate change. Therefore, there is an utmost importance to assess the current profile of water use in the irrigation scheme and to device some workable strategies under future situations of land use and climate change. This study aims to investigate the spatio-temporal status of water utilization and performance of irrigation system using remote sensing data and techniques (SEBAL) in combination with other point data. Different irrigation performance indicators including equity, adequacy and reliability using evaporation fraction as main input parameter are utilized. Current profiles of land use/land cover (LULC) areas are assessed and their change detections are worked out to establish realistic future scenarios. Spatially distributed seasonal net recharge, a very important input parameter for groundwater modeling, is estimated by employing water balance approaches using spatial data from remote sensing and local norms. Such recharge results are also compared with a water table fluctuation approach. Following recharge estimation, a regional 3-D groundwater flow model using FEFLOW was set up. This model was calibrated by different approaches ranging from manual to automated pilot point (PP) approach. Sensitivity analysis was performed to see the model response against different model input parameters and to identify model regions which demand further improvements. Future climate parameters were downscaled to establish scenarios by using statistical downscaling under IPCC future emission scenarios. Modified recharge raster maps were prepared under both LULC and climate change scenarios and were fed to the groundwater model to investigate groundwater dynamics. Seasonal consumptive water use analysis revealed almost double use for kharif as compared to rabi cropping seasons with decrease from upper LCC to lower regions. Intra irrigation subdivision analysis of equity, an important irrigation performance indicator, shows less differences in water consumption in LCC. However, the other indicators (adequacy and reliability) indicate that the irrigation system is neither adequate nor reliable. Adequacy is found more pronounced during kharif as compared to rabi seasons with aver-age evaporation fraction of 0.60 and 0.67, respectively. Similarly, reliability is relatively higher in upper LCC regions as compared to lower regions. LULC classification shows that wheat and rice are major crops with least volatility in cultivation from season to season. The results of change detection show that cotton exhibited maximum positive change while kharif fodder showed maximum negative change during 2005-2012. Transformation of cotton area to rice cultivation is less conspicuous. The water consumption in upper LCC regions with similar crops is relatively higher as compared to lower regions. Groundwater recharge results revealed that, during the kharif cropping seasons, rainfall is the main source of recharge followed by field percolation losses, while for rabi cropping seasons, canal seepage remains the major source. Seasonal net groundwater recharge is mainly positive during all kharif seasons with a gradual increase in groundwater level in major parts of LCC. Model optimization indicates that PP is more flexible and robust as compared to manual and zone based approaches. Different statistical indicators show that this method yields reliable calibration and validation as values of Nash Sutcliffe Efficiency are 0.976 and 0.969, % BIAS are 0.026 and -0.205 and root mean square errors are 1.23 m and 1.31 m, respectively. Results of model output sensitivity suggest that hydraulic conductivity is a more influential parameter in the study area than drain/fillable porosity. Model simulation results under different scenarios show that rice cultivation has the highest impact on groundwater levels in upper LCC regions whereas major negative changes are observed for lower parts under decreased kharif fodder area in place of rice, cotton and sugarcane. Fluctuations in groundwater level among different proposed LULC scenarios are within ±1 m, thus showing a limited potential for groundwater management. For future climate scenarios, a rise in groundwater level is observed for 2011 to 2025 under H3A2 emission regime. Nevertheless, a drop in groundwater level is expected due to increased crop consumptive water use and decreased precipitations under H3A2 scenario for the periods 2026-2035 and 2036-2045. Although no imminent threat of groundwater shortage is anticipated, there is an opportunity for developing groundwater resources in the lower model regions through water re-allocation that would be helpful in dealing water shortages. The groundwater situation under H3B2 emission regime is relatively complex due to very low expectation of rise in groundwater level through precipitation during 2011-2025. Any positive change in groundwater under such scenarios is mainly associated with changes in crop consumptive water uses. Consequently, water management under such situation requires revisiting of current cropping patterns as well as augmenting water supply through additional surface water resources.:ABSTRACT VIII ZUSAMMENFASSUNG X ACRONYMS 1 Chapter 1 3 GENERAL INTRODUCTION 3 1 Groundwater for irrigated agriculture 3 2 Groundwater development in Pakistan 4 3 Study area 6 4 History of groundwater use in the study area 7 5 Research agenda 8 5.1 Problem statement 8 5.2 Objectives and scope of the study 9 Chapter 2 12 OVERVIEW OF PUBLICATIONS 12 Chapter 3 16 GENERAL CONCLUSIONS AND POLICY RECOMMENDATIONS 16 REFERENCES 20 ANNEXES 23 ACKNOWLEDGEMENTS 123