The changes in the frequency of daily precipitation in Urmia Lake basin, Iran

Bavil, Sepideh Salehi; Zeinalzadeh, Kamran; Hessari, Behzad

doi:10.1007/s00704-017-2177-7

Cited by 14 publications

(4 citation statements)

References 30 publications

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“…As a result, the former missed the effect of changes in pattern or precipitation frequency within a month. This changes were recently reported by Bavil et al (2018) and Hosseini-Moghari et al (2018) based on analysis of daily precipitation. Bavil et al (2018) stated the frequency on precipitation event less than 5 mm/day increase significantly over basin during past decades.…”

Section: C9supporting

confidence: 82%

Answer to SC2

Hosseini‐Moghari¹

2018

Preprint

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In their analysis, authors only considered the time period 2003-2013. It is not clear why both earlier years and the most recent years are excluded from the analysis. It is well-known that there has been significant changes in the basin and the lake water level since late 1990s. Using a statistical change point analysis, Khazaei et al. [in review] identified the year 2000 as the beginning of the period with significant changes in the lake dynamics. So, it is crucial to include all the years post 2000âȂŤthe data availability is not an issue as ULRP now provides researchers with required data. For instance, annual inflows to the lake are highly variable during this period (see the supplement figure), which you also used for calibrating the model. Given such degree of variability, the modelling results are likely sensitive to this variable, and it is important to use the entire time period. Response: Data required for our analysis, except the data you mentioned, is not available before 2000. For example, GRACE satellite was only launched in 2002, and irrigated area reported by ULRP starts from 2001 and ends in 2012 (see Figure 16 in Kamali et al. (2015)). In addition, there are many gaps in groundwater data before 2000. If we want to work only on long term inflow or estimated water use based on empirical equations, we would have repeated the works were done by Shadkam et al. (2016) and Chaudhari et al. (2018), respectively. Furthermore, Iran Water Resources Management Company release data are available with two/three years' delay. Thus, in addition to irrigated area, in situ groundwater data precipitation are not available for the recent years. To sum up, be sure to perform a multi-objective calibration, we consider maximum time interval. Comment#2: You have assumed that the irrigated area in 2013 remains the same as 2012. This assumption is wrong and known to be wrong, as we know that the irrigated area has increased since 2012. Chaudhari et al. [2018] estimated the cropland area of the basin using both MODIS and HYDE 3.1 products (also notice the difference between these two products on Fig 3). Land use change is a major driver in this basin. Expansion of the irrigated area has increased the evapotranspiration losses, and con-C2 HESSD Interactive comment

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Section: C9supporting

confidence: 82%

Answer to SC2

Hosseini‐Moghari¹

2018

Preprint

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“…Therefore, the very high human contribution to the lake volume decline of 86 % determined by Chaudhari et al (2018) may arise from the poor performance of the uncalibrated model. In addition, Chaudhari et al (2018) studied a considerably longer period, i.e., 1995-2010, that includes the change point of lake dynamic (the year 2000 based on Khazaei et al, 2019and 2001, based on Fazel et al, 2017. Although including years prior to 2000 might be lead to different results, some other studies like Shadkam et al (2016) and Farokhnia et al (2018), whose modeling included years 2000 and 2001, support the results of the current study.…”

Section: Distinguishing the Contributions Of Human Water Use And Climmentioning

confidence: 99%

“…In previous hydrological modeling studies of Lake Urmia basin, either there was no model calibration or calibration was only done using a single observation type, in particular surface water inflow into the lake. Although streamflow observations are very informative for hydrological modeling as they integrate over processes in the whole upstream basin, a good fit of simulated and observed streamflow may not necessarily lead to an appropriate simulation of other flows and storages (Beven and Freer, 2001). Moreover, additional types of observations have to be added to reduce the possibility of equifinality (Döll et al, 2016;Kelleher et al, 2017;Khatami et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Quantifying the impacts of human water use and climate variations on recent drying of Lake Urmia basin: the value of different sets of spaceborne and in situ data for calibrating a global hydrological model

Hosseini‐Moghari

Araghinejad

Tourian

et al. 2020

Hydrol. Earth Syst. Sci.

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Abstract. During the last decades, the endorheic Lake Urmia basin in northwestern Iran has suffered from declining groundwater tables and a very strong recent reduction in the volume of Lake Urmia. For the case of Lake Urmia basin, this study explores the value of different locally and globally available observation data for adjusting a global hydrological model such that it can be used for distinguishing the impacts of human water use and climate variations. The WaterGAP Global Hydrology Model (WGHM) was for the first time calibrated against multiple in situ and spaceborne data to analyze the decreasing lake water volume, lake river inflow, loss of groundwater, and total water storage in the entire basin during 2003–2013. The calibration process was done using an automated approach including a genetic algorithm (GA) and non-dominated sorting genetic algorithm II (NSGA-II). Then the best-performing calibrated models were run with and without considering water use to quantify the impact of human water use. Observations encompass remote-sensing-based time series of annual irrigated areas in the basin from MODIS, monthly total water storage anomaly (TWSA) from GRACE satellites, and monthly lake volume anomalies. In situ observations include time series of annual inflow into the lake and basin averages of groundwater level variations based on 284 wells. In addition, local estimates of sectoral water withdrawals in 2009 and return flow fractions were utilized. Calibration against MODIS and GRACE data alone improved simulated inflow into Lake Urmia but inflow and lake volume loss were still overestimated, while groundwater loss was underestimated and seasonality of groundwater storage was shifted as compared to observations. Lake and groundwater dynamics could only be simulated well if calibration against groundwater levels led to an adjustment of the fractions of human water use from groundwater and surface water. Thus, in some basins, globally available satellite-derived observations may not suffice for improving the simulation of human water use. According to WGHM simulations with 18 optimal parameter sets, human water use was the reason for 52 %–57 % of the total basin water loss of about 10 km3 during 2003–2013, for 39 %–43 % of the Lake Urmia water loss of about 8 km3, and for up to 87 %–90 % of the groundwater loss. Lake inflow was 39 %–45 % less than it would have been without human water use. The study shows that even without human water use Lake Urmia would not have recovered from the significant loss of lake water volume caused by the drought year 2008. These findings can support water management in the basin and more specifically Lake Urmia restoration plans.

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“…Since 1976 winter precipitation has shown no significant trend, but spring has become wetter with drier summers (Mills, 2016). Bavil et al (2018) investigated the trend in the frequency of occurrence of precipitation in Urmia Lake basin in Iran and concluded that the frequency of occurrence of daily precipitation with small amounts (<5 mm) is showing a significant increasing trend while the frequency of occurrence for larger amounts (>10 mm) is significantly decreasing resulting in reduced runoff to the lake. Significant decreasing trends are observed in the annual rainfall in West and North Africa with an abrupt reduction since 1968 (Nicholson et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Interannual variations in rainfall of different intensities in South West of Western Australia

Philip

2019

Intl Journal of Climatology

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Significant decreases in rainfall in South West of Western Australia (SWWA) over recent decades are of concern for water supply and agricultural production in the region. Total rainfall can be decomposed into light, medium and heavy rainfalls, and the land responds differently to these rainfall classes. Little, however, is known about changes in different rainfall classes in SWWA.The objective of this study is to quantify contributions from these rainfall classes to the decrease and interannual variations in rainfall, and to relate the decreases to station characteristics, that is, latitude, elevation and the mean annual rainfall, and to the large scale circulation pattern known as the Southern Annular Mode (SAM). Long-term data for 30 stations were used, and daily rainfall was divided into three classes in such a way that they contributed equally (one third of the total) for each station. Trend and correlation analysis was applied to these classes. The decrease in heavy rainfall was mainly responsible for the decrease in total rainfall, followed by the medium and light rainfalls. The rate of decrease in heavy rainfall was 68% higher than, while that in light rainfall was about half, of the expected trend. Heavy rainfall exhibited a significant decreasing trend in winter and autumn but mildly increasing trend in summer. The number of heavy rain days also showed a significant decreasing trend. The rate of decrease relative to the mean was similar for both heavy rainfall and number of heavy rain days. Stations with a higher rainfall were more likely to experience a decrease in rainfall than those in the drier inland areas. Stations where rainfall was strongly correlated with SAM were mostly concentrated along the west coast of SWWA. The SAM index explained 9% of the variation in heavy rainfall and 11% in total rainfall for the region.

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The changes in the frequency of daily precipitation in Urmia Lake basin, Iran

Cited by 14 publications

References 30 publications

Answer to SC2

Answer to SC2

Quantifying the impacts of human water use and climate variations on recent drying of Lake Urmia basin: the value of different sets of spaceborne and in situ data for calibrating a global hydrological model

Interannual variations in rainfall of different intensities in South West of Western Australia

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