Integrating Landsat TM/ETM+ and Numerical Modeling to Estimate Water Temperature in the Tigris River under Future Climate and Management Scenarios

Abstract

Modeling the water quality of rivers and assessing the effects of changing conditions is often hindered by a lack of in situ measurements for calibration. Here, we use a combination of satellite measurements, statistical models, and numerical modeling with CE-QUAL-W2 to overcome in situ data limitations and evaluate the effect of changing hydrologic and climate conditions on water temperature (Tw) in the Tigris River, one of the largest rivers in the Middle East. Because few in situ estimates of Tw were available, remotely-sensed estimates of Tw were obtained from Landsat satellite images at roughly 2 week intervals for the year 2009 at the upstream model boundary (Mosul Dam) and two locations further downstream, Baeji and Baghdad. A regression was then developed between air temperature and Landsat Tw in order to estimate daily Tw. These daily Tw were then used for the upstream model boundary condition and for model calibration downstream. Modeled Tw at downstream locations agreed well with Landsat-based statistical estimates with an absolute mean error of <1 °C. A model sensitivity analysis suggested that altering upstream river discharge had little impact on downstream Tw. By contrast, a climate change scenario in which air temperatures were increased by 2 °C resulted in a 0.9 °C and 1.5 °C increase in Tw at Baeji and Baghdad, respectively. Since Tw is a fundamental state variable in water quality models, our approach can be used to improve water quality models when in situ data are scarce.

Identifying stream temperature variation by coupling meteorological, hydrological, and water temperature models

“…Correspondingly, several studies considering mountainous North American streams have reported annual stream temperature increases of 0.03–0.5°C/year (e.g., Hari et al, 2006; Pekarova et al, 2008). A study to estimate future temperatures of the Tigris River (one of the largest rivers in the Middle East) under an increasing air temperature scenario of 2.0°C resulted in a 0.9 and 1.5°C increase in water temperature at Baeji and Baghdad, respectively (Al‐Murib et al, 2019). Ren et al (2020) discovered that water temperature decreased in summer and increased in winter, and there was a time delay in water temperature processes in reservoirs in the Yellow River, China.…”

Hydrodynamic and Total Dissolved Solids Model of the Tigris River Using CE-QUAL-W2

“…Modeled temperatures had an AME at several locations including Tharthar Lake of about 1 o C using satellite estimates of inflow and in situ temperatures. A full description of the temperature modeling in the Tigris River is shown in Al Murib (2018) and in Al- Murib et al (2019).…”

Hydrochemical Evaluation of the Tigris River from Kut to Amara sites, Iraq

“…The TDS is a primary factor in the water quality evaluation [11]. Several researchers have inspected the river discharges by applying a variety of methods and approaches [11] [12][13] [14]. These studies have indicated how some anthropogenic activities have had the main reason for the dissolved sediment transported in the river [14] [15] [16] [17] [18].…”

“…Several researchers have inspected the river discharges by applying a variety of methods and approaches [11] [12][13] [14]. These studies have indicated how some anthropogenic activities have had the main reason for the dissolved sediment transported in the river [14] [15] [16] [17] [18]. The effect of the global climatic warming on the chemistry of the Tigris River from the years 2005 to 2010 is investigated and considered a novelty of the present work.…”