Distribution patterns of soluble salts and gypsum in soils under large-scale irrigation agriculture in Central Asia

The global distribution patterns of 14918 geo-referenced occurrences from 394 living brachiopod species were mapped in 5° grid cells, which enabled the visualization and delineation of distinct bioregions and biodiversity hotspots. Further investigation using cluster and network analyses allowed us to propose the first systematically and quantitatively recognized global bioregionalization framework for living brachiopods, consisting of five bioregions and thirteen bioprovinces. No single environmental or ecological variable is accountable for the newly proposed global bioregionalization patterns of living brachiopods. Instead, the combined effects of large-scale ocean gyres, climatic zonation as well as some geohistorical factors (e.g., formation of land bridges and geological recent closure of ancient seaways) are considered as the main drivers at the global scale. At the regional scale, however, the faunal composition, diversity and biogeographical differentiation appear to be mainly controlled by seawater temperature variation, regional ocean currents and coastal upwelling systems.

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Takhtajan's floristic regions and foliicolous lichen biogeography: a compatibility analysis

The Lichenologist ◽

10.1006/lich.2002.0430 ◽

2003 ◽

Vol 35 (1) ◽

pp. 33-53 ◽

Cited By ~ 28

Author(s):

Robert Lücking

Keyword(s):

Large Scale ◽

New Caledonia ◽

Vascular Plant ◽

Distribution Patterns ◽

Plant Distribution ◽

Sufficient Information ◽

East African ◽

Foliicolous Lichens ◽

North East ◽

Compatibility Analysis

AbstractTakhtajan's floristic regions of the world, based on vascular plant distribution, were used for a comparative analysis of foliicolous lichen biogeography. Of the 35 regions distinguished by that author, 23 feature foliicolous lichens. The South-East African, Fijian, Polynesian and Hawaiian regions lack sufficient information and were excluded from further analysis. Using multi-dimensional scaling and cluster and cladistic analyses, the remaining 19 regions were grouped into six lichenogeographical regions: (1) Neotropics, (2) African Paleotropics (including Madagascar, Réunion and Seychelles), (3) Eastern Paleotropics (including North-East Australia and New Caledonia), (4) Valdivian region (temperate rainforest in southern South America), (5) Tethyan region (subtropical areas of Macaronesia, Mediterranean, and Western Irano-Turanian) and (6) Neozealandic-Tasmanian region (temperate rainforests of New Zealand and Tasmania). Affinities between these six large scale regions, with 57–77% shared species, are still stronger than those between the 35 smaller scale regions denned by Takhtajan [(20−)40–60(−75)% shared species]. Based on presence/absence within each of the six regions, 22 potential distribution patterns were defined for foliicolous lichens. Many species are widely distributed; 21% are cosmopolitan or pantropical, while 19% are disjunct on at least two continents, and only 60% are restricted to one of the three major tropical areas (nearly 100% in vascular plants). Most of the latter are found in the Neotropics, while the African Paleotropics are poor in endemics. Most genera deviate significantly from overall distribution patterns; for example, Strigula and Calopadia have higher proportions of widely distributed species, while Porina displays a concentration of Eastern Paleotropical endemics. Species diversity and composition of the six regions indicate that the three extra-tropical foliicolous lichen biotas (Valdivian, Tethyan, Neozealandic-Tasmanian) are the result of partly separate evolutionary histories. On the other hand, there is a strong affinity between the Neotropics and the African Paleotropics, suggesting a shared Western Gondwanan element in the foliicolous lichen biotas of these two regions.

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Post-Soviet changes in irrigated crop production in the Amu Darya Basin

10.5194/egusphere-egu21-16266 ◽

2021 ◽

Author(s):

Daniel Müller ◽

Andrey Dara ◽

Christopher Krause ◽

Mayra Daniela Peña-Guerrero ◽

Tillman Schmitz ◽

...

Keyword(s):

Water Resources ◽

Central Asia ◽

Crop Production ◽

Large Scale ◽

Aral Sea ◽

Crop Cultivation ◽

Amu Darya ◽

Crop Type ◽

Water Scarce ◽

Hydrological Droughts

<p>Water withdrawals for irrigated crop production constitute the largest global consumer of blue water resources. Monitoring the dynamics of irrigated crop cultivation allows to track changes in water consumption of irrigated cropping, which is particularly paramount in water-scarce arid and semi-arid areas. We analyzed changes in irrigated crop cultivation along with occurrence of hydrological droughts for the Amu Darya river basin of Central Asia (534,700 km<sup>2</sup>), once the largest tributary river to the Aral Sea before large-scale irrigation projects have grossly reduced the amount of water that reaches the river delta. We used annual and seasonal spectral-temporal metrics derived from Landsat time series to quantify the three predominant cropping practices in the region (first season, second season, double cropping) for every year between 1988 and 2020. We further derived unbiased area estimates for the cropping classes at the province level based on a stratified random sample (n=2,779). Our results reveal a small yet steady decrease in irrigated second season cultivation across the basin. Regionally, we observed a gradual move away from cotton monocropping in response to the policy changes that were instigated since the mid-1990s. We compared the observed cropping dynamics to the occurrence of hydrological droughts, i.e., periods with inadequate water resources for irrigation. We find that areas with higher drought risks rely more on irrigation of the second season crops. Overall, our analysis provides the first fine-scale, annual crop type maps for the irrigated areas in the Amu Darya basin. The results shed light on how institutional changes and hydroclimatic factors that affect land-use decision-making, and thus the dynamics of crop type composition, in the vast irrigated areas of Central Asia.</p>

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Mitigation of Climate Change Impacts Through Treatment and Management of Low Quality Water for Irrigation in Pakistan

Environmental and Agricultural Informatics ◽

10.4018/978-1-5225-9621-9.ch053 ◽

2020 ◽

pp. 1181-1198

Author(s):

Ghulam Murtaza ◽

Muhammad Saqib ◽

Saifullah ◽

Muhammad Zia-ur-Rehman ◽

Muhammad Naveed ◽

...

Keyword(s):

Climate Change ◽

Ground Water ◽

Large Scale ◽

River Flow ◽

Indus Basin ◽

Change Scenario ◽

Soluble Salts ◽

Quality Water ◽

To Come ◽

Carry Over

The Indus Plains of Pakistan are situated in arid to semi-arid climate where monsoon rains are erratic and mostly fall in the months of July and August. These rains are not only insufficient to grow even a single crop without artificial irrigation but also cause flood havoc very frequently that is associated with the climate change. The Indus river transports water for agriculture, industry and domestic usage within the basin and downstream. The Indus Basin is among the few basins severely affected by global warming and resulting climate change. The alteration in temporal and spatial patterns of rainfall has resulted in unexpected drought and floods. About 70 to 80% of total river flows occur in summer season due to snow melt and monsoonal rainfalls. Lack of storage reservoirs has decreased the ability to regulate flood water as well as its potential use during the drought season along with cheap hydro-electricity generation. The sedimentation in the system has limited the storage capacity of the existing three reservoirs by 28%. Consequently carry over capacity of these storage structures is only 30 days compared to 120 to 220 days in India and 900 days in Colorado Basin. Pakistan is facing shortage of good quality water due to competition among agricultural and non-agricultural sectors, this scenario will continue rather will further aggravate in future. According to the climate change scenario, the warming is reflected in the river-flow data of Pakistan, especially during the past 2-3 decades. To bridge the gap between fresh water availability and demand, ground water is being pumped to meet the irrigation requirements of crops. The pumped ground water (70-80%) is brackish and could become a sustainability issue in the long run. The prolonged agricultural uses of such water will deteriorate soils, crops and human living environments. Water quality parameters usually considered include electrical conductivity (EC) for total soluble salts, and sodium adsorption ratio (SAR) and residual sodium carbonate (RSC) reflect the sodicity hazards. In order to limit or even to eliminate adverse effects of such waters, certain treatment and/or management options are considered as important pre-requisites. For bringing down high concentration of total soluble salts, dilution with good quality water is the doable practice. To decrease high SAR of irrigation water, a source of calcium is needed, dilution (with good quality water) will decrease SAR by the square root times of the dilution factor, while use of acids will be cost-intensive rather may adversely impact the soil health. For high RSC, dilution with low CO32-+HCO3- water will serve the purpose, addition of Ca-salts will raise Ca2++Mg2+ to bring a decrease in water RSC, while acids will neutralize CO32-+HCO3- to lower water RSC. Gypsum is the most economical and safe amendment while acids could also decrease RSC but at higher relative cost. City wastewater and seed priming in aerated gypsum solution is also presented. Such practices at small and/or large scale surely will help a lot to sustain the food security and the environment in the days to come where climate change has to be experienced round the world. Therefore, a well-coordinated program is necessary to create awareness among different sections of the society including the policy makers, general public, organizations, industrialists and farmers.

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Irrigation agriculture in Central Asia: a long-term perspective from Turkmenistan

The Archaeology of Drylands ◽

10.4324/9780203165737-17 ◽

2003 ◽

pp. 129-146

Keyword(s):

Central Asia ◽

Irrigation Agriculture

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Variability of the Cold Season Climate in Central Asia. Part II: Hydroclimatic Predictability

Journal of Climate ◽

10.1175/jcli-d-18-0892.1 ◽

2019 ◽

Vol 32 (18) ◽

pp. 6015-6033 ◽

Cited By ~ 5

Author(s):

Lars Gerlitz ◽

Eva Steirou ◽

Christoph Schneider ◽

Vincent Moron ◽

Sergiy Vorogushyn ◽

...

Keyword(s):

Central Asia ◽

Snow Cover ◽

Large Scale ◽

Cold Season ◽

Hadley Cell ◽

Quasi Biennial Oscillation ◽

Large Variability ◽

Forecast Performance ◽

Eurasian Snow Cover ◽

Eurasian Snow

Abstract Central Asia (CA) is subjected to a large variability of precipitation. This study presents a statistical model, relating precipitation anomalies in three subregions of CA in the cold season (November–March) with various predictors in the preceding October. Promising forecast skill is achieved for two subregions covering 1) Uzbekistan, Turkmenistan, Kyrgyzstan, Tajikistan, and southern Kazakhstan and 2) Iran, Afghanistan, and Pakistan. ENSO in October is identified as the major predictor. Eurasian snow cover and the quasi-biennial oscillation further improve the forecast performance. To understand the physical mechanisms, an analysis of teleconnections between these predictors and the wintertime circulation over CA is conducted. The correlation analysis of predictors and large-scale circulation indices suggests a seasonal persistence of tropical circulation modes and a dynamical forcing of the westerly circulation by snow cover variations over Eurasia. An EOF analysis of pressure and humidity patterns allows separating the circulation variability over CA into westerly and tropical modes and confirms that the identified predictors affect the respective circulation characteristics. Based on the previously established weather type classification for CA, the predictors are investigated with regard to their effect on the regional circulation. The results suggest a modification of the Hadley cell due to ENSO variations, with enhanced moisture supply from the Arabian Gulf during El Niño. They further indicate an influence of Eurasian snow cover on the wintertime Arctic Oscillation (AO) and Northern Hemispheric Rossby wave tracks. Positive anomalies favor weather types associated with dry conditions, while negative anomalies promote the formation of a quasi-stationary trough over CA, which typically occurs during positive AO conditions.

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Quantitative Soil Wind Erosion Potential Mapping for Central Asia Using the Google Earth Engine Platform

Remote Sensing ◽

10.3390/rs12203430 ◽

2020 ◽

Vol 12 (20) ◽

pp. 3430

Author(s):

Wei Wang ◽

Alim Samat ◽

Yongxiao Ge ◽

Long Ma ◽

Abula Tuheti ◽

...

Keyword(s):

Wind Speed ◽

Central Asia ◽

Wind Erosion ◽

Large Scale ◽

Google Earth ◽

Geospatial Data ◽

Aral Sea ◽

Erosion Modeling ◽

Soil Wind Erosion ◽

Google Earth Engine

A lack of long-term soil wind erosion data impedes sustainable land management in developing regions, especially in Central Asia (CA). Compared with large-scale field measurements, wind erosion modeling based on geospatial data is an efficient and effective method for quantitative soil wind erosion mapping. However, conventional local-based wind erosion modeling is time-consuming and labor-intensive, especially when processing large amounts of geospatial data. To address this issue, we developed a Google Earth Engine-based Revised Wind Erosion Equation (RWEQ) model, named GEE-RWEQ, to delineate the Soil Wind Erosion Potential (SWEP). Based on the GEE-RWEQ model, terabytes of Remote Sensing (RS) data, climate assimilation data, and some other geospatial data were applied to produce monthly SWEP with a high spatial resolution (500 m) across CA between 2000 and 2019. The results show that the mean SWEP is in good agreement with the ground observation-based dust storm index (DSI), satellite-based Aerosol Optical Depth (AOD), and Absorbing Aerosol Index (AAI), confirming that GEE-RWEQ is a robust wind erosion prediction model. Wind speed factors primarily determined the wind erosion in CA (r = 0.7, p < 0.001), and the SWEP has significantly increased since 2011 because of the reversal of global terrestrial stilling in recent years. The Aral Sea Dry Lakebed (ASDLB), formed by shrinkage of the Aral Sea, is the most severe wind erosion area in CA (47.29 kg/m2/y). Temporally, the wind erosion dominated by wind speed has the largest spatial extent of wind erosion in Spring (MAM). Meanwhile, affected by the spatial difference of the snowmelt period in CA, the wind erosion hazard center moved from the southwest (Karakum Desert) to the middle of CA (Kyzylkum Desert and Muyunkum Desert) during spring. According to the impacts of land cover change on the spatial dynamic of wind erosion, the SWEP of bareland was the highest, while that of forestland was the lowest.

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