# Groundwater and Urban Planning Perspective
## 3 Discussion of Urban Planning and Subsidence
### Analysis of the Subsidence Triggering Factors in Clotentina River Corridor
Therefore, when the lake's water level decreased 2 m from November 2014 to April 2016, a negative displacement of more than 20 mm occurred at the ground surface. An offset of a few months can be observed between the water level and ground displacement trends. This is due to the different behavior of the surface water and of the groundwater. Considering the linear trendline for Floreasca Lake and for the ground displacements, for medium decrease of 1.5 m in the water lake, 15 mm of subsidence is registered. The Soseaua Nordului area has similar characteristics to the aforementioned ones, more precisely, it has neighboring areas with anthropogenic deposits and areas with land-cover changes in the vicinity due to construction activity. The main difference is that the construction work in the Soseaua Nordului area includes office buildings along with apartment buildings. A peculiarity of the area is the fact that it was partially affected by land displacements during 2004-2010. Figure 11 shows the comparison between the evolution of Herastrau Lake water level and the land displacement trend of this area. Herastrau Lake is the only lake of Coletina River where the water level increases periodically (controlled). It is evident that there is a slight reverse correspondence between the two data series. Although the general trend of the vertical displacements shows subsidence, during the periods when the lake water level registers minimum values, the values of the terrain surface displacements have a slight ascending trend followed by a descending trend. During periods when the lake water level has maximum values, the terrain surface shows a descending trend followed by a slight rising trend. \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline Name of the **Area** & **PSIS 51** & **SoshaThe obtained results show a major concordance between the water level of the lakes and the vertical displacements of the surrounding areas, both with decreasing tendencies, in the context of a strong hydraulic connection between the Colentina riverbed and the shallow aquifer strata. The presence of anthropogenic deposits associated with groundwater fluctuations showed amplified ground vertical displacements, compared to the areas where natural deposits exist. Another association that can produce land movements is provided by the presence of marshy soils as a base layer for heterogeneous anthropogenic deposits. In all the areas mentioned above, these observations lead to the necessity for further local studies [65] in order to properly discriminate between the phenomena and processes generating subsidence. Civil engineers and urban planners should use these studies to further investigate local geology and possible anthropogenic strata, the ground geotechnical properties, and the local hydrogeological settings. These studies, providing an accurate  
Figure 11: Comparison between the Herästrau Lake water level and the evolution of the land vertical displacements in Soseaua Nordului area. Source: elaborated by the authors. Figure 10: Comparison between the Floreasca Lake water level and the evolution of the land vertical displacements in the Gara Herästrau area. Source: elaborated by the authors. overview of the ground conditions, should be included as support for the general urban plans of the cities, documenting future developments.