
Stephan SchulzTechnical University of Darmstadt | TU · Hydrogeology
Stephan Schulz
Dr. rer. nat.
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54
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Introduction
Additional affiliations
November 2011 - January 2016
Publications
Publications (54)
Whether hydroclimatic extremes cause yield losses or failures not only depends on their intensity but also on local environmental conditions. These conditions shape the capacity to buffer climatic shocks and thus necessitate a regionally specific impact assessment and adaptation planning. However, the degree to which different environmental conditi...
Climate change has far-reaching impacts on water availability globally, with changing precipitation patterns and global warming contributing to increasing scarcity and unreliability of spring water in many regions. Despite this understanding, the implication of climate change on the hydrological system remains limited in certain areas, including th...
Despite regulatory measures, nitrogen contamination in groundwater remains a global environmental and health concern. Denitrifying bacteria play a crucial role, particularly in the capillary fringe, in reducing nitrogen loads through two primary pathways: heterotrophic and autolithotrophic. While the former relies on labile organic carbon as an ele...
To mitigate groundwater level decline, managed aquifer recharge (MAR) with secondary treated wastewater (STWW) is increasingly considered and implemented. However, the effectiveness and potential risks of such systems need evaluation prior to implementation. In this study, we present a large-scale sand tank experiment to analyse processes related t...
Due to the difficulties in estimating groundwater recharge and cross‐boundary nature of many aquifers, estimating groundwater recharge at large scale has been called upon. Process‐based models as well as data‐driven models have been established to meet this need. Meanwhile, with the advent of explainable artificial intelligence (XAI) methods, data‐...
Sorption of hydrophobic organic contaminants onto thermally altered carbonaceous materials (TACM) constitutes a widely used technology for remediation of polluted waters. This process is typically described by sorption isotherms, with one of the most used models, the Polanyi-Dubinin-Manes (PDM) equation, including water solubility (Sw) as a normali...
Contamination of groundwater with pharmaceutical active compounds (PhACs) increased over the last decades. Potential pathways of PhACs to groundwater include techniques such as irrigation, managed aquifer recharge, or bank filtration as well as natural processes such as losing streams of PhACs-loaded source waters. Usually, these systems are charac...
The popular chloride mass balance (CMB) method is often praised for its simplicity, especially in the groundwater recharge context. While some involved variables are indeed easy to obtain, the required atmospheric (wet/dry) chloride deposition is difficult to quantify. A literature survey, conducted for Africa and the Middle East, revealed surprisi...
In the Rafsanjan plain, Iran, the excessive use of groundwater for pistachio irrigation since the 1960s has led to a severe water level decline as well as land subsidence. In this study, the advantages of InSAR analyses and groundwater flow mod-eling are combined to improve the understanding of the subsurface processes causing groundwater-related l...
Biogeochemical redox processes control the chemical behavior of many major and trace elements, making their comprehension crucial for predicting and protecting environmental health. Nitrogen (N) is especially susceptible to changes in soil redox conditions and affects the cycles of other redox‐sensitive species. Elevated N concentrations, in nitrat...
Lake Urmia in north-western Iran was once one of the world's largest hyper-saline lakes and represented a unique ecosystem for a number of endangered species. The lake's shrinking over the past decades has attracted considerable attention and several studies have addressed its water balance. Yet, evaporation of shallow groundwater from the dried-up...
This study presents a lake bed elevation model of Lake Urmia. In the course of model generation, a time series of the extent of the lake surface was derived from 129 satellite images with different acquisition dates based on the Landsat sensors Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Operational Land Imager (OLI). Due to the...
The integrated distributed hydrological model ParFlow-CLM was used to predict water and energy transport between subsurface, land surface, and atmosphere for the Stettbach headwater catchment, Germany. Based on this model, a global sensitivity analysis was performed using the Latin-Hypercube (LH) sampling strategy followed by the One-factor-At-a-Ti...
There is still limited understanding of where stream water originates, their flow paths, how water sources mix, and for how long water transits montane tropical catchments. Here, we used a simple gamma convolution integral model (GM), ensemble hydrograph separation (EHS) and a tracer‐aided model (TAM) to assess runoff generation, mixing processes a...
Due to limited availability of surface water, many arid and semi-arid countries have to rely on their groundwater resources. Despite the quasi-absence of present-day replenishment, some of these aquifers contain large amounts of water that was recharged during wetter periods in the past. Although these recharge events often occurred several thousan...
There is still limited understanding of how waters mix, where waters come from and for how long they reside in tropical catchments. In this study, we used a tracer-aided model (TAM) and a gamma convolution integral model (GM) to assess runoff generation, mixing processes, water ages and transit times (TT) in the pristine humid tropical rainforest Q...
Information on water balance components such as evapotranspiration and groundwater recharge are crucial for water management. Due to differences in physical conditions, but also due to limited budgets, there is not one universal best practice, but a wide range of different methods with specific advantages and disadvantages. In this study, we propos...
Environmental chambers are used for a variety of experiments in multiple disciplines but are often prohibitively expensive. In this study, we developed an environmental chamber that allows reliable regulation of temperature and relative humidity in a range typical for warm climatic conditions. As we have only used consumer products, which are readi...
Lake Urmia is one of the largest hypersaline lakes on earth with a unique biodiversity. Over the past two decades the lake water level declined dramatically, threatening the functionality of the lake’s ecosystems. There is a controversial debate about the reasons for this decline, with either mismanagement of the water resources, or climatic change...
Calibrating a spatially distributed hydrological model of a region with complex and highly diverse agricultural settings is a difficult task. It becomes even more challenging, if major parts of the hydrology are human controlled, e.g. through irrigation agriculture. In this study, a Soil and Water Assessment Tool (SWAT) was set up and calibrated fo...
Many hydrologic studies require data on the oxygen and hydrogen stable isotope composition (δ¹⁸O, δ²H) of precipitation and various collector designs have been suggested for gathering corresponding samples. Yet, it is crucial that these collectors, also known as totalizers, prevent evaporation and associated isotope fractionation. Surprisingly, we...
More than half of the human population currently lives in urban areas and according to the
United Nations, cities will be the living space of an additional 2.5 billion people by the year 2050
(UN, 2015b). The proportion and speed of this urban growth increase the pressure on water
resources, and this is often seen negatively. However, this challeng...
Due to limited availability of surface water, many arid to semi-arid countries rely on their groundwater resources. Despite the quasi-absence of present day replenishment, some of these groundwater bodies contain large amounts of water, which was recharged during pluvial periods of the Late Pleistocene to Early Holocene. These mostly fossil, non-re...
In view of the substantial costs associated with classic monitoring networks, participatory data collection methods can be deemed a promising option to obtain complementary data. An emerging trend in this field is social media mining, i.e., harvesting of pre-existing, crowd-generated data from social media. Although this approach is participatory i...
In arid regions like the Arabian Peninsula, available water resources are essentially restricted to groundwater, requiring a detailed understanding of the local and regional hydrogeological conditions and water budgets. In the framework of the IWAS initiative, the 1.8 × 106 km2 large sedimentary Upper Mega Aquifer of the Arabian Peninsula was chose...
The major groundwater resources of the Arabian Peninsula are stored in the large sedimentary basins in its eastern part. Evaporation from continental salt pans (playas) is an important process in water resources assessments of its upper principal aquifers – the Upper Mega Aquifer system – as it constitutes a significant sink. However, literature va...
Groundwater is the principal water resource in semi-arid and arid environments. Therefore, quantitative estimates of its replenishment rate are important for managing groundwater systems. In dry regions, karst outcrops often show enhanced recharge rates compared to other surface and sub-surface conditions. Areas with exposed karst features like sin...
Only limited data on the isotopic and chemical composition of Riyadh rain are currently available. In this study, we complement these data by analyzing integral samples covering 28 precipitation events between 2009 and 2013. Results of stable isotope analyses are used to establish a Local Meteoric Water Line: δ2H=5.22(±0.38)·δ18O+14.8(±0.9) ‰. Mois...
Groundwater is the principal water resource in most dryland areas. Therefore, its replenishment rate is of great importance for water management. The amount of groundwater recharge depends on the climatic conditions, but also on the geological conditions, soil properties and vegetation. In dryland areas, outcrops of karst aquifers often receive enh...
The Dahl Hith cave is located approximately 30 km southeast of Riyadh, the capital of Saudi Arabia. In the past decades, the groundwater table exposed inside the cave became subject to appreciable changes. After a decline due to agricultural water abstraction for irrigation purposes, the water table exhibited a rapid rise in the last few years. Con...
Arid countries like Saudi Arabia often depend on fossil groundwater. Hence, thorough studies of the available resources are crucial. In the course of such investigations, analyses of δ18O and δD are frequently applied to constrain the provenance of the waters and to reconstruct the (paleo)climatic conditions during their recharge. Yet, to be able t...
A 3D groundwater flow model merges all relevant hydrogeological information. Thus, it became a powerful management tool, which serves the purpose of understanding a system and calculating scenarios. Especially for the countries on the Arabian Peninsula, which rely on groundwater resources, those models became important in order to achieve a better...
Sabkhas are salt flats with a shallow saline water table. Generally, it is possible to distinguish between two types of sabkha - coastal and inland. On the Arabian Peninsula, coastal sabkhas are located along the coastline of the Arabian Gulf. Inland sabkhas predominantly occur in the eastern part of the Rub’ Al Khali desert. Generally, sabkha soil...
Pollution and overexploitation of scarce groundwater resources is a serious problem in the Zarqa River catchment, Jordan. To estimate this resource’s potential, the amount and spatial distribution of groundwater recharge was calculated by applying the hydrological model J2000. The simulation period is composed of daily values gathered over a 30-yea...
Poster presentation at European Geosciences Union (EGU) General Assembly 2013, Vienna.
Arid regions like the Arabian Peninsula are limited on water resources. Hence, it is important to estimate the water balance components. On the Arabian Shelf an important natural sink term are Sabkhas (salt flats) from which shallow saline groundwater evaporates...
Water resources are strongly limited in semi-arid to arid regions and
groundwater constitutes often the only possibility for fresh water for
the population and industry. An understanding of the hydrological
processes and the estimation of magnitude of water balance parameters
also includes the knowledge of processes of groundwater recharge. For
the...
Groundwater is the only relevant freshwater resource for most countries
on the Arabian Peninsula. Due to almost no recharge in most of the areas
a sustainable management of this resource is not possible. Nevertheless,
a smart and intelligent mining of groundwater can extend its lifetime.
For this purpose groundwater models can be applied as powerfu...