scholarly journals Increasy eutrophication symptoms during a prolonged drought event in tropical semi-arid reservoirs, Brazil

RBRH ◽  
2021 ◽  
Vol 26 ◽  
Author(s):  
Diógenes Fernandes dos Santos ◽  
Jonathan Mota da Silva ◽  
Vanessa Becker
Keyword(s):  
Trophic State ◽  
Temporal Trend ◽  
Standardized Precipitation Index ◽  
Principal Component ◽  
Water Volume ◽  
Drought Event ◽  
Drought Period ◽  
Prolonged Drought ◽  
The Standardized Precipitation Index ◽  
Semi Arid

ABSTRACT Eutrophication is a global problem and an important cause of the ecological health degradation of aquatic ecosystems. The aim was to evaluate the effect of prolonged drought period (2012 to 2019) on the trophic state of two Brazilian semi-arid reservoirs, Boqueirão de Parelhas (BOQ) and Passagem das Traíras (TRA). The work was carried out according to a drought classification system, based on the Standardized Precipitation Index (SPI), with an aggregated timescale of 36 months, defining three periods. In the Period I, higher values of Secchi and lower values of turbidity, solids, nutrients and chlorophyll-a were registered, when compared to the other periods, mainly in BOQ. The principal component analyses of both reservoirs reveled a showed a temporal trend of the sample units according to the consequences of the prolonged drought. The results indicated changes in limnological variables due to the reduction of accumulated water volume, and they demonstrated that prolonged droughts impact the intensification of eutrophication in both systems. The trophic state of the BOQ reservoir was changed from mesotrophic to eutrophic as a consequence of the drought, while in TRA the eutrophic state remained, but with more intensified symptoms, with higher concentration values of nutrients, solids and algal biomass.

scholarly journals Caractérisation à l’aide du SPI de la Sécheresse climatique dans le bassin versant de Ziz (Sud-Est, Maroc)

2018 ◽  
Vol 14 (21) ◽  
pp. 177 ◽  
Author(s):  
Radouan Mehdaoui ◽  
El-Mostafa Mili ◽  
Aziz Seghir
Keyword(s):  
Temporal Variability ◽  
Standardized Precipitation Index ◽  
Winter Season ◽  
Spatial And Temporal Variability ◽  
Drought Period ◽  
North Eastern ◽  
Edge Part ◽  
The Standardized Precipitation Index ◽  
Bassin Versant ◽  
Eastern Edge

This paper analyzes the spatial and temporal variability of drought in winter season in an arid geographical gradient located in the eastern edge part of the Moroccan High Atlas especially at the Ziz watershed. Drought period between 1975 and 2013 were analyzed using the Standardized Precipitation Index (SPI) over 12 months for a 38-year scale. The results indicate that the most important drought by intensity and duration occurred during the 1982/84, 1983/84, 2000/01, and 2004/05 periods are generalized on all stations of the basin with a minimum SPI reached -2.77 at the Taous station. The results indicate that drought in winter have been tied to the dominance of dry circulation with the exception of the frequency of thermodynamic and north-eastern disturbances which are considered unstable aerological conditions. Which occur frequently between February and April of each year for the Errachidia station, Hassan Adakhil Dam, Foum Zaabal, Tillicht, M'Zizl, Arfoud and Taouz.

scholarly journals Extreme droughts drive tropical semi-arid eutrophic reservoirs towards CO2 sub-saturation

2018 ◽  
Vol 30 (0) ◽  
Author(s):  
Jurandir Rodrigues de Mendonça Júnior ◽  
André Megali Amado ◽  
Luciana de Oliveira Vidal ◽  
Arthur Mattos ◽  
Vanessa Becker
Keyword(s):  
Carbon Dioxide ◽  
Water Level ◽  
Chlorophyll A ◽  
Co2 Reduction ◽  
Water Volume ◽  
Drought Period ◽  
Autotrophic Metabolism ◽  
Semi Arid Region ◽  
Carbon Dioxide Co2 ◽  
Semi Arid

Abstract Aim: This study aimed to evaluate the carbon dioxide (CO2) dynamics in tropical semi-arid reservoirs during a prolonged drought period as well as to test if the trophic state affects the CO2 saturation. Methods This study was performed in four reservoirs located in the tropical semi-arid region in the northeast of Brazil. All samplings were performed between 9 and 12 am using a Van Dorn Bottle. Samples for partial pressure of carbon dioxide (pCO2 ) measurements were taken in the sub-surface as well as samples for total phosphorus and chlorophyll-a. Correlation analysis and linear regression were used to detect relations among the calculated pCO2, water volume and chlorophyll-a. Results The water level reduction due to atypical droughts caused chlorophyll-a concentrations to increase, which in turn, led to CO2 reduction in the water. However, CO2 concentrations were very variable and an alternation between CO2 sub-saturation and super-saturation conditions was observed. This paper showed that water volume and chlorophyll-a were important regulators of CO2 in the water, as well as important carbon balance predictors in the tropical semiarid reservoirs. Conclusions The results of this paper indicate that the eutrophication allied to drastic water level reductions lead to a tendency of autotrophic metabolism of these systems.

Impact of meteorological drought on agriculture in the Tensift watershed of Morocco

2019 ◽  
Vol 11 (4) ◽  
pp. 1323-1338 ◽  
Author(s):  
Modeste Meliho ◽  
Abdellatif Khattabi ◽  
Guy Jobbins ◽  
Fathallah Sghir
Keyword(s):  
Agricultural Production ◽  
Temporal Evolution ◽  
Standardized Precipitation Index ◽  
Meteorological Drought ◽  
Water Shortage ◽  
Water Volume ◽  
Annual Crops ◽  
Irrigated Area ◽  
The Standardized Precipitation Index ◽  
The Impact

Abstract Located in the mid-west of Morocco, the Tensift watershed shelters the Takerkoust dam, which provides a part of the water used for irrigation of the N'fis agricultural area, which is an important irrigated area of the Tensift watershed. This study deals with the impact of droughts on water inflows to the Takerkoust dam and how the water shortage caused by droughts affects agricultural production in the N'Fis area. The standardized precipitation index (SPI) was used to illustrate the temporal evolution of drought periods. The trend observed on data showed that the Tensift watershed experienced a succession of droughts and humid periods of varying intensities. Periods of drought have negatively affected water inflows to the Takerkoust dam, and therefore the amount of water allocated to agricultural irrigation. Years that experienced droughts showed a restriction of more than 50% of water volume planned for irrigation. During periods of water scarcity, farmers reduce or completely avoid irrigation of annual crops to save water for irrigation of perennial crops. The water shortage for irrigation has led in some cases to a drop of up to 100% of the surface allocated to the production of annual crops.

scholarly journals Effectiveness of abundance and biomass curves in detecting environmental alterations in semi-arid region reservoirs

2018 ◽  
Vol 18 (2) ◽  
Author(s):  
Carlinda Raílly Medeiros ◽  
Evaldo de Lira Azevêdo ◽  
José Etham de Lucena Barbosa ◽  
Joseline Molozzi
Keyword(s):  
Arid Region ◽  
Water Resource Management ◽  
Environmental Indicators ◽  
Water Volume ◽  
Severe Drought ◽  
Drought Period ◽  
Littoral Region ◽  
Semi Arid Region ◽  
Effective Diagnosis ◽  
Semi Arid

Abstract For mitigation of environmental problems generated by bad water resource management, the first step is to develop methods for effective diagnosis. The potential bioindicator, mainly in the benthic community, in the evaluation of water quality is the structure of the community, associated with magnitude of environmental impact. The aim of the present study was to evaluate the effectiveness of abundance biomass curves (ABC) as tools to estimate ecological quality in reservoirs in the Brazilian semi-arid region. Two reservoirs, Epitácio Pessoa and Argemiro de Figueiredo were selected. These reservoirs are located in the watershed of the Paraíba River, in Northeast Brazil. Sampling was done at 40 sites in the littoral region of each reservoir, during the periods of higher and lower water volume in the reservoirs. ABC for semi-arid region reservoirs showed disparate results for biological and environmental indicators, because they had a better relationship with momentary variables (physical and chemical parameters). This may be related to the high occurrence of exotic species, principally Corbicula largillierti, which has a high biomass, in association with a severe drought period. ABC must thus be used with parsimony and combined with other indicators, for an accurate and coherent characterization.

scholarly journals Drought Frequency Analysis Based on the Development of a Two-Variate Standardized Index (Rainfall-Runoff)

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2599 ◽  
Author(s):  
Gholamreza Nikravesh ◽  
Mohammad Aghababaei ◽  
Mohammad Nazari-Sharabian ◽  
Moses Karakouzian
Keyword(s):  
Standardized Precipitation Index ◽  
Drought Indices ◽  
Flow Index ◽  
Severe Drought ◽  
Drought Event ◽  
Rainfall Runoff ◽  
Drought Duration ◽  
Novel Approach ◽  
Standardized Index ◽  
The Standardized Precipitation Index

Drought is one of the most drastic events, which has imposed irreparable damages on human societies and may occur in any climate regime. To define drought, given its properties of multidimensionality and randomity, one cannot rely on a single variable/index (e.g., precipitation, soil moisture, and runoff). Accordingly, implementing a novel approach, this study investigated drought events in two basins with different climatic regimes, using multivariate frequency analyses of drought duration, severity, and severity peak, based on developing a Two-variate Standardized Index (TSI). The index was developed based on the concept of copula, by applying rainfall-runoff data (1974–2019) and comparing them with two popular drought indices, the Standardized Precipitation Index (SPI) and Standardized Stream Flow Index (SSFI), in terms of derived drought characteristics. The results show that TSI determined more severe drought conditions with fewer return periods than SPI and SSFI in a specific drought event. This implies that the disadvantages of SPI and SSFI might not be found in TSI. The developed index can be employed by policymakers and planners to protect water resources from drought.

scholarly journals Dry and Wet Events in Andean Populations of Northern Peru: A Case Study of Chachapoyas, Peru

2021 ◽  
Vol 9 ◽  
Author(s):  
Jesús Rascón ◽  
Wildor Gosgot Angeles ◽  
Lenin Quiñones Huatangari ◽  
Manuel Oliva ◽  
Miguel Ángel Barrena Gurbillón
Keyword(s):  
Anthropogenic Activities ◽  
Standardized Precipitation Index ◽  
Population Increase ◽  
Severe Drought ◽  
Drought Event ◽  
Climatic Data ◽  
Economic Activities ◽  
The North ◽  
Moderate Drought ◽  
The Standardized Precipitation Index

Climate change and population growth have heavily impacted the ecosystem’s water resources, essential for anthropogenic activities. These also apply to the Andean city of Chachapoyas, located in the north of Peru, which has gone through a substantial population increase in recent years, therefore increasing its water demand. This research aimed to assess dry and wet events from 1981 to 2019 that have taken place in Chachapoyas, by applying the Standardized Precipitation Index (SPI), and the Standardized Precipitation Evapotranspiration Index (SPEI). These events were periodically characterized, and the index relationship was determined at different timescales. The SPI and SPEI indices were calculated at the city’s only weather station for timescales of 3, 6, 12, and 24 months using climatic data. The indices showed a remarkably consistent behavior for timescales of 12 and 24 months detecting an extreme drought event in 1993, while for timescales of 3 and 6 months a severe drought event was detected in the same year. Contrastingly, there has been an increase in extreme wet events in the last decade, hence Chachapoyas is categorized between "moderate drought" and “moderate wet”. It should be noted that the indices have a high correlation between them when calculated for the same timescale. The results were statistically significant (p < 0.05). Considering the results obtained related to dry and wet events and their relation with economic activities such as environmental management, we can conclude that the SPI and SPEI indices are useful and valuable tools for local and regional governments.

scholarly journals Extreme Droughts Change in the Mekong River Basin: A Multidisciplinary Analysis Based on Satellite Data

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2682
Author(s):  
Vo Tuong ◽  
Thanh-Van Hoang ◽  
Tien-Yin Chou ◽  
Yao-Min Fang ◽  
Chun-Tse Wang ◽  
...  
Keyword(s):  
River Basin ◽  
Regional Climate ◽  
Standardized Precipitation Index ◽  
Extreme Drought ◽  
Mekong River ◽  
Drought Duration ◽  
Mekong River Basin ◽  
Drought Period ◽  
Mk Test ◽  
The Standardized Precipitation Index

This study evaluates droughts in the Mekong River Basin (MKB) based on a multidisciplinary method, mainly using the Standardized Precipitation Index (SPI) and Mann–Kendall (MK) test. Precipitation data corresponding to the seasonality of the regional climate were retrieved from Integrated Multi-satellitE Retrievals for Global Precipitation Measurement from 2001 to 2020, at a monthly temporal scale and 0.1 degree spatial resolution. Drought events and their average interval, duration, and severity were determined based on Run theory. Our results revealed the most extreme drought period was in January 2014, at the time the lowest precipitation occurred. Spatial extreme drought results indicated that Zone 2 in the upstream MKB has the highest frequency of drought, with 44 events observed during 19 years, and experiences the most severe droughts, whereas Zone 24 in the downstream MKB has the most prolonged drought duration of seven months. The periods and locations of extreme drought were identified using the SPI, corresponding to historic droughts of the MKB. Furthermore, the MK test shows an increasing trend of droughts in the lower MKB and the cluster analysis identified six clusters of times series. Overall, our study provides essential findings for international and national water resource stakeholders in identifying trends of extreme drought in the MKB.

scholarly journals Water volume reduction increases eutrophication risk in tropical semi-arid reservoirs

2018 ◽  
Vol 30 (0) ◽  
Author(s):  
Carlos Alberto Nascimento da Rocha Junior ◽  
Mariana Rodrigues Amaral da Costa ◽  
Rosemberg Fernandes Menezes ◽  
José Luiz Attayde ◽  
Vanessa Becker
Keyword(s):  
River Basin ◽  
Trophic State ◽  
Secchi Depth ◽  
Freshwater Ecosystems ◽  
Volume Reduction ◽  
Water Volume ◽  
Temperature And Precipitation ◽  
Time Substitution ◽  
Linear Regressions ◽  
Semi Arid

Abstract Aim Global patterns of temperature and precipitation have significantly changed over the last century and nearly all predictions point to even greater changes by the end of 2100. Long periods of drought in semi-arid regions generally reduce reservoirs and lakes water level, increasing the nutrients concentrations in the water. Our principal hypothesis is that water volume reduction, driven by prolonged droughts, will increase reservoirs susceptibility to eutrophication and accordingly an increase in trophic state. To test this hypothesis, we used a comparative analysis of ecosystems in a space-for-time substitution approach, in a Brazilian semi-arid region, to predict the consequences of reservoirs water volume reduction on key limnological variables. Methods We sampled 16 reservoirs located in two sub-basins with contrasting rainfall regimes, inserted on Piranhas-Açu watershed. The Seridó River basin (SB) is dry and the Piancó River basin (SB) is humid, with annual mean precipitation of 500 and 700 mm, respectively. Linear regressions analyzes were performed to assess whether the percentage of maximum volume stored (%MVS) is a good predictor for total phosphorus (TP), total nitrogen (TN) and chlorophyll-a (CHLA). In addition, a two factorial analysis of variance (two-way ANOVA) was performed to test for period (dry, very dry and extremely dry), basin (SB and PB) and their interactions effects on TP, TN, CHLA, conductivity, turbidity, and Secchi depth. Results The results showed a reduction in the reservoirs %MVS both for PB and SB regions. At the extremely dry period, all reservoirs were classified as eutrophic, but TP concentrations reached much higher values in SB than in PB. The linear regressions analyses showed that the TP and TN were negatively related to %MVS during all periods sampled. The two-way ANOVA showed that there were significant basin and period effects on TP, TN, Secchi depth and turbidity, whereas for CHLA and conductivity only basin effects were observed. In addition, we found significant interaction effects between period and basin on TP, TN and turbidity. Conclusions We conclude that the contrasting levels of rainfall observed between the two basins affect the water quality and trophic state of the reservoirs and these effects are magnified by water volume reduction. Therefore, our findings might help to predict the consequences of rainfall reductions on freshwater ecosystems of Brazilian drylands.

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