Temporal Dynamics of Land Use and Water Quality in Three Sub-Catchments of the Rur River, Germany

The Rur catchment has over time undergone land 
use change which could have affected the biogeochemical processes of the river. 
Three sub-catchments in the Rur, Upper Rur, 
Inde and Wurm have different kinds of land use. Upper Rur is more natural 
catchment; Inde is mixed type and Wurm is highly modified by anthropogenic activities. This study 
investigated how land use changes from 2000 
to 2018 have influenced SO4 and Cl dynamics in the Rur catchment. Land use maps were developed in QGIS environment for land use change 
calculation. Historical water quality data were collected from the online 
public source by Ministry of Environment and Nature Conservation in Germany. 
R-software was used for statistical analysis and graphical presentation. Less 
land use change was observed in the Upper Rur between 2000 to 2018. But in the 
Inde and Wurm decrease in agricultural land and associated increase in industrial, commercial and urban land were 
observed. Increase in mining area inside the catchment has enhanced the 
level of SO4 and EC in the Inde river. Conversion rates of natural 
to human dominated land use could be quantified in this study through land use change mapping, which will further help in making water management plan for these and 
comparable German and European catchments. However, high quality 
historical data set is a key requirement to maximize the output in process of 
relating impact of land use change in water quality.


Introduction
It has been accepted globally that activities on the terrestrial ecosystem strongly How to cite this paper: Adhikari, S. (2020). Temporal Dynamics of Land Use and Water Quality in Three Sub-Catchments of the Rur River, Germany. Journal of Geoscience and Environment Protection,8,[36][37][38][39][40][41][42][43][44][45][46][47] influences the hydrological processes (Cuo et al., 2013;Recha et al., 2013). After the Second World War, there was a rapid population growth in European countries, which caused expansion of urban areas, intensification in agriculture and development of large chemical and electrical industries. This helped to develop large cities in Meuse river basin (Tu et al., 2005;Lambin & Gheist, 2006). The Rur River, one of the tributaries to the Meuse River, has also undergone land use land cover change (LULCC) which might influence in stream hydro-chemical processes of the Rur River (Rodolfo et al., 2018).
Land use change is mostly occurring to enhance the economic value of that land and this might lead to ecological degradation (Paul & Rashid, 2017). LULCC shows the interaction between the natural environment and human activities and when the land use changes continuously it causes land cover change (Gaitanis et al., 2015;Kanianska et al., 2014). Socio-economic factor, policy-regulation and nature conservation factors are the common drivers of land use change in Europe (Ustsoglu & Williams, 2017). It is important to find out the dynamics of the global land use to maintain environmental sustainability (Gaitanis et al., 2015).
LULCC such as, enhanced agricultural practices and urbanization will lead to water quality degradation through more soil erosion, sediment load, leaching of nutrients, leaching from wastewater treatment plants and industrial effluents. The results in increased oxygen depletion, growth of cyanobacteria, fish killing and increase in waterborne diseases (Foley et al., 2005).
The River Continuum Concept (RCC) explains about the variation of organic matter throughout the longitudinal dimension of the river (Vannote et al., 1980). But the anthropogenic alteration in its riparian land use can disturb the river continuum along with its quality and quantity of water (Nautiyal & Mishra, 2013).
Similar activities can be observed in the Rur catchment, where origin part of the river is still in natural condition. But the downstream areas are modified for agriculture, urban settlements, and industries. In this case, concept of Urban Stream Syndrome (USS) helps to describe how urbanized catchments have influenced the ecological and hydrological characteristics of a river (Meyer et al., 2005). And Urban Watershed Continuum (UWC) enables us to understand how urban growth impacts on watershed functions. It also considers how long-term changes and continues growth of infrastructures are associated with characteristics of urban streams (Kaushal & Belt, 2012).

Concept of Land Use and Land Cover Change (LULCC) in a River Catchment
LULCC of a catchment have been taken as important topic of environmental research (Cai, 2001). When the vegetated ground coverage is changed to concrete land, biogeochemical alteration occurs in a catchment (Yu et al., 2016). Urban expansion is major activity which increases heavy metals, organic matter, sediments and nutrients to the river (Wang et al., 2014;Sharma et. al., 2005). Different drivers of LULCC can be either social or natural such as demography,  (Zondag & Brosboom, 2009;Liu et al., 2010). Landscapes and land use types are diverse topographical areas which consists of interlink between human actions and the environment (Kumar et al., 2018).
By finding out the trend of LULCC we can predict impacts in river water quality as well as water issues that might occur in future (Lambin, 1997). Different ecosystem services provided by river like water quality regulation, biodiversity conservation, CO 2 sequestration and microclimate regulation will be degraded by LULCC (Lambin et al., 2000). Among various processes for collecting data about catchment health, LULCC mapping by the use of GIS (Geographical Information System) and RS (Remote Sensing) are commonly used tools (Tekle & Hedlund, 2000), which helps in making strategic management plan for water resource management (ESCAP, 1997). The Rur River catchment has diverse type of land uses in different sub-catchments. There is waste water discharge from 1.1 million local inhabitants and from industries while intensive agriculture is also taking place in large flat terrain (Schulze & Matthies, 2001;Waldhoff et al., 2017). Thus, this research mainly focuses to find the LULCC in this area and its impact on river water quality variables such as SO 4 , Cl and EC.

Site Description
Rur River passes through three different countries; Belgium, Germany, and the  Rur: Upper Rur, Inde and Wurm were selected to focus this study in different land use. Where Upper Rur is more natural with higher percentage of forest area. Inde is mixed type catchment with mining areas, human influenced and forested areas. The Wurm is the northernmost catchment highly influenced by human activities (WVER, 2018).

Upper Rur
The Upper Rur is the origin area of the Rur River which has High Fens area (an area which was declared as a nature reserve in 1957 situated in high mountain plateau region at Liege province of Belgium. It is a typical plain area with high annual rainfall. This place is rich in peatland which is important for water storage. Then the river flows through Rhenish Uplands which is a low mountain type of river. The sediments of this part of the river consist of gravels particles brought from the mountain areas (WVER, 2018).

Inde
The Inde River originates from eastern part of Belgium in High Fens area. The Wurm River rises from the forest of Aachen and when it reaches to the urban areas, it passes through underground channel and starts flowing openly when it reaches the northern periphery of the city. There it mixes other piped waters from city areas and it flows through 25 km of channelized way. After that, it goes towards the border areas of Herzogenrath, Wurselen, Kerkrade, Ubach-Palenberg, Geilenkirchen and finally joins to Rur River at Heinsberg-Kempen.
Since it was piped along the city areas, the bed sediments have less coarse gravel particles but as the river reaches to Ubach-Palenberg, coarse rocks can be found as bed material (WVER, 2018).

Mapping Land Use Change
Land use and land cover change maps were prepared with the help of satellite image from Coordination of Information on the Environment (CORINE). The land use maps were developed by using QGIS. CORINE land cover baseline map of whole Europe of 2000 and 2018 were used for making land use maps of three sub-catchments and calculating change in area of each land use class. First of all three sub-catchments were delineated, than land use map of 2000 and 2018 were developed for these three catchments. Area of different land use types were calculated by using spatial analysis tool in QGIS. Which helped to find the land use change in three sub-catchments from 2000 to 2018.

Collection of Past Water Quality Data
Past water quality data were obtained from the the record of (MENC, 2018). It is the website which has a record of water quality data from different stations in the Rur catchment. Regular sampling sites at the outlet of each catchment were selected to observe the long-term change in water quality. As Upper Rur is more natural than the Inde and Wurm, it was taken as reference site. Which helped to relate the change in land use with change in water quality. For finding the trend of change in concentration of SO 4 and Cl, simple linear regression model was used. R-software was used for statistical analysis and graphical presentation.

Results
Land use change calculation from 2000 to 2018 shows that Upper Rur had minimal change than the Inde and Wurm (Figure 2)

Discussion
Difference in rate of change in land use in three different sub-catchments indicates the variation in human activities taking place within the Rur catchment.  Remarkable change in land use like increase in settlement and agricultural area, decrease in wetlands and forest area over past thirty eight years was observed in Koga watershed in Ethiopia (Sewnet & Gebeyehu, 2018). Similar change was also observed in Xiaotjiang watershed in China (Jiang et al., 2008). In Europe, remarkable conversion of agricultural area to urban area has occurred in these two decades and some parts of the Netherlands, Belgium, Poland and UK are even facing challenge of rapid urban growth (Van Vliet et al., 2015;Ustsoglu & Williams, 2017). The trend of decline in agricultural area and increase in urban area in the Rur catchment indicates possible future impact in biodiversity, ecosystem services, soil and aquatic environment. Finding from similar research from Europe says when agricultural area is changed to settlements or industries, it will affect the overall sustainability of environment leaving negative impact in all biotic and abiotic components (Van Vliet et al., 2015). And this might influence the target of sustainable development goal to protect all the surface water by 2030. ). Observations of this study from the Upper Rur, Inde and Wurm shows that the target of maintaining benchmark of water quality variables in these rivers by 2030 can be achieved by proper monitoring and action, especially in the Inde and Wurm river flowing through catchments with higher human activities.

Conclusion
From the observation of land use maps of 2000 and 2018, it can be concluded

R E T R A C T E D
S. Adhikari that land use change is happening in different parts of the Upper Rur, Inde and Wurm. Conversion of agricultural land to urban area and increase in industrial and commercial area are noticeable land use change in the study area. After observation of increasing trend in SO 4 and EC in last two decades time period in the outlet point (I14) of Inde River, it can be concluded that increase in opencast lignite mining supplemented by increased urban, industrial and commercial area is affecting the river water quality. It can also be concluded that the Upper Rur catchment is in more natural state which has helped in maintaining good river water quality. From this study, it can also be concluded that good set of historical data set is required for relating land use change with different water quality variables.