How to identify groundwater-caused thermal anomalies in lakes based on multi-temporal satellite data in semi-arid regions

Mallast, Ulf; Gloaguen, Richard; Friesen, Jan; Rödiger, Tino; Geyer, Stefan; Merz, Ralf; Siebert, Christian

doi:10.5194/hess-18-2773-2014

Cited by 31 publications

(30 citation statements)

References 39 publications

(61 reference statements)

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“…Groundwater temperatures remain rather stable during the course of the year and they are only minimally influenced by ambient air temperature changes (Mallast et al 2013). In contrast, the general temperature of the DS underlies a clear atmospherical influence resulting in minimum temperatures of *22°C between December and March and maximum temperatures of *33°C between July and September (Hact and Gertman 2003).…”

Section: Study Area and Groundwater Flowmentioning

confidence: 99%

“…The larger atmosphere column for the present case of the DS (-400 m msl.) causes a non-linear reduction of the absolute SST of *2-4 K (Mallast et al 2013;Stanhill 1990). Note that the temperature represents the skin temperature of the water and, therefore, less than 1 mm of the uppermost water layer.…”

Section: Study Area and Groundwater Flowmentioning

confidence: 99%

“…(McFeeters 1996). The further processing of data is explicitly elucidated in Mallast et al (2013) and is subsequently only summarised.…”

Section: Study Area and Groundwater Flowmentioning

confidence: 99%

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Localisation and temporal variability of groundwater discharge into the Dead Sea using thermal satellite data

et al. 2013

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The semi-arid region of the Dead Sea heavily relies on groundwater resources. This dependence is exacerbated by both population growth and agricultural activities and demands a sustainable groundwater management. Yet, information on groundwater discharge as one main component for a sustainable management varies significantly in this area. Moreover, discharge locations, volume and temporal variability are still only partly known. A multi-temporal thermal satellite approach is applied to localise and semi-quantitatively assess groundwater discharge along the entire coastline. The authors use 100 Landsat ETM ? band 6.2 data, spanning the years between 2000 and 2011. In the first instance, raw data are transformed to sea surface temperature (SST). To account for groundwater intermittency and to provide a seasonally independent data set DT (maximum SST range) per-pixel within biennial periods is calculated subsequently. Groundwater affected areas (GAA) are characterised by DT \ 8.5°C. Unaffected areas exhibit values[10°C. This allows the exact identification of 37 discharge locations (clusters) along the entire Dead Sea coast, which spatially correspond to available in situ discharge observations. Tracking the GAA extents as a direct indicator of groundwater discharge volume over time reveals (1) a temporal variability correspondence between GAA extents and recharge amounts, (2) the reported rigid ratios of discharge volumes between different spring areas not to be valid for all years considering the total discharge, (3) a certain variability in discharge locations as a consequence of the Dead Sea level drop, and finally (4) the assumed flushing effect of old Dead Sea brines from the sedimentary body to have occurred at least during the two series of

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Section: Study Area and Groundwater Flowmentioning

confidence: 99%

Section: Study Area and Groundwater Flowmentioning

confidence: 99%

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Localisation and temporal variability of groundwater discharge into the Dead Sea using thermal satellite data

et al. 2013

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“…This reduces influences of potential outliers evoked through e.g. thin clouds and represents an advancement described in Mallast et al (2014) (Grasshoff et al 2009). In August 2016, September 2016, October 2016 and November 2016 nitrate was determined in freshwater samples within a couple of days after sampling at the Geochemistry Laboratory, Dept.…”

Section: Subsurface Hydrologymentioning

confidence: 99%

“…All applied scenes reflect the local wet season and represent low-tide 20 status in the years 2013/2014. The pre-processing chain besides the automatic and tide-controlled scene selection is described in Mallast et al (2014).…”

Section: Subsurface Hydrologymentioning

confidence: 99%

Timing of land–ocean groundwater nutrient fluxes from a tropical karstic region (southern Java, Indonesia)

Oehler

Eiche

Putra

et al. 2017

Preprint

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Abstract. 10In tropical karstic regions, knowledge about the timing and quantity of land-ocean groundwater nutrient fluxes is important, as those nutrients may affect coastal ecosystems and contaminate coastal springs. High aquifer permeability of the karst, combined with high recharge and discharge during heavy rain events, leads to a close connectivity between groundwater in the hinterland and the coastal zone. The alteration between drier periods and heavy rain events can lead to a high temporal variability of groundwater discharge associated nutrient fluxes from the 15 hinterland towards the coastal. We studied the timing of land-ocean groundwater nutrient fluxes in the tropical karstic region of Gunung Kidul (southern Java Indonesia) from November 2015 until December 2016. Satellite infrared imagery revealed two major areas of direct submarine and coastal groundwater discharge. δ 18 O and δD signatures, nutrient concentrations, combined with precipitation and groundwater discharge data, indicate a rapid groundwater recharge and transport from the catchment area towards the coastal ocean. Measured groundwater 20 discharge rates varied from less than 1 m³/s up to 16.6 m³/s and were dominantly controlled by recharge in the hinterland and surface infiltration during the rainy season. Nitrate fluxes ranged from 5 x 10 3 to 139 x 10 3 mol/day and DSi fluxes from 50 x 10 3 to 310 x 10 3 mol/day. High nitrate concentrations coinciding with phases of high discharge lead to particularly high nitrate fluxes. This counterintuitive temporal connection might be due to fertilization during the onset of the wet season and the retention of nutrients from untreated sewage in the soil and in 25 sinkholes during dryer periods, which are then washed into the aquifer during heavy rain events. In the tropical karstic region of southern Java, extraordinarily high land-ocean nutrient fluxes occur therefore during the onset of periods with high discharge, which makes coastal water and coastal springs prone to contamination during this time, while flood recession and dry periods are characterized by lower nutrient fluxes. In tropical karstic regions the timing of land-ocean groundwater nutrient fluxes is thus highly variable, which may lead to ecological implications. High 30 nutrient fluxes during certain times of the year may explain the sudden occurrence of harmful algae blooms in coastal environments and have to be considered in coastal groundwater management.

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Discharge estimation of submarine springs in the Dead Sea based on velocity or density measurements in proximity to the water surface

Munwes

Geyer

Katoshevski

et al. 2019

Hydrological Processes

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The Dead Sea is a closed lake, the water level of which is lowering at an alarming rate of about 1 m/year. Factors difficult to determine in its water balance are evaporation and groundwater inflow, some of which emanate as submarine groundwater discharge. A vertical buoyant jet generated by the difference in densities between the groundwater and the Dead Sea brine forms at submarine spring outlets. To characterize this flow field and to determine its volumetric discharge, a system was developed to measure the velocity and density of the ascending submarine groundwater across the center of the stream along several horizontal sections and equidistant depths while divers sampled the spring. This was also undertaken on an artificial submarine spring with a known discharge to determine the quality of the measurements and the accuracy of the method. The underwater widening of the flow is linear and independent of the volumetric spring discharge. The temperature of the Dead Sea brine at lower layers primarily determines the temperature of the surface of the upwelling, produced above the jet flow, as the origin of the main mass of water in the submarine jet flow is Dead Sea brine. Based on the measurements, a model is presented to evaluate the distribution of velocity and solute density in the flow field of an emanating buoyant jet. This model allows the calculation of the volumetric submarine discharge, merely requiring either the maximum flow velocity or the minimal density at a given depth.

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How to identify groundwater-caused thermal anomalies in lakes based on multi-temporal satellite data in semi-arid regions

Cited by 31 publications

References 39 publications

Localisation and temporal variability of groundwater discharge into the Dead Sea using thermal satellite data

Localisation and temporal variability of groundwater discharge into the Dead Sea using thermal satellite data

Timing of land–ocean groundwater nutrient fluxes from a tropical karstic region (southern Java, Indonesia)

Discharge estimation of submarine springs in the Dead Sea based on velocity or density measurements in proximity to the water surface

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