GEOSPATIAL ANALYSIS OF THE DIGITAL ELEVATION MODEL (DEM) OF THE KHOREZM OASIS

296 GEOSPATIAL ANALYSIS OF THE DIGITAL ELEVATION MODEL (DEM) OF THE KHOREZM OASIS Boymurodov R.Z, Matchanov M.J, Odamboyeva I.D, Egamberganova G.U Urgench State University named after Abu Raykhan Beruni DOI: https://doi.org/10.5281/zenodo.17393030 Abstract: This thesis is an in-depth analysis of a digital elevation model of the Khorezm oasis, a historically and agriculturally significant region of Central Asia, located mainly in the territories of the present-day Republics of Uzbekistan and Turkmenistan. The map, centered on the lower reaches of the Amu Darya, is a remarkable geospatial representation of the complex relationships between topography, hydrology, and human settlements. By examining elevation data, hydrological features, and man-made structures, the study describes the fundamental ecological situation that has characterized the Khorezm oasis for millennia. Keywords: Geographic Information System, Digital elevation model, Oasis. Annotatsiya: Ushbu tezis asosan hozirgi Oʻzbekistonda va Turkmaniston Respublikalari hududlarida joylashgan hamda Markaziy Osiyoning tarixiy va qishloq xoʻjaligi jihatidan ahamiyatli hududi boʻlgan Xorazm vohasining raqamli balandlik modelining chuqur tahlilidir. Markazi Amudaryoning quyi qismida joylashgan xarita topografiya, gidrologiya va aholining yashash joylari oʻrtasidagi murakkab munosabatlarning ajoyib geofazoviy tasviridir. Balandlik ma'lumotlari, gidrologik xususiyatlar va texnogen tuzilmalarni o'rganish orqali tadqiqot ming yillar davomida Xorazm vohasini tavsiflab kelgan fundamental ekologik vaziyatni tavsiflaydi. Kalit so‘zlar: Geografik axborot tizimi, Raqamli balandlik modeli, Voha. The Khorezm oasis is located in the lower part of the Amudarya, from latitude 50° 41' to 54° 14' latitude, longitude from 64° 54' to 68° 21' longitude (Figure 1). Khorezm region of Uzbekistan, Karakhalpakhstan's southwest portion, and Turkmenistan's northeastern portion of Tashkhovuz region comprise the Khorezm oasis. [1,2,3] Digital elevation models (DEMs) and Geographic Information Systems (GIS) collectively provide powerful methods of examining topographic and hydrologic characteristics of watersheds. DEMs are terrain elevation data that can be processed by GIS technology to obtain basic watershed characteristics like flow direction, flow accumulation, watershed delineation, slopes, and travel times [4]. GIS-based DEM analysis enables efficient computation of geomorphological attributes such as aerial extent, slope, relief, aspect, and drainage network, replacing the cumbersome manual calculations from topographic maps [5]. These techniques form the basis of practical applications such as erosion modeling, where composite thematic layers derived from DEMs can identify erosion-prone areas in watersheds [6]. Apart from that, DEM processing in GIS also facilitates the derivation of various hydrological parameters like Topographic Wetness Index (TWI), Terrain Ruggedness Index (TRI), Stream 297 Power Index (SPI), and stream density, which are pre-requisites for hydrological modeling and geo-environmental hazard mapping. Figure 1. Digital Elevation Model (DEM) map of the Khorezm oasis. Analysis of the digital elevation model of the Khorezm oasis shows that, the most straightforward feature of the DEM is the highly level nature of the region. The elevations, ranging from approximately 38 meters asl in the northwestern sections of the region to about 473 meters in the far south, reveal a generally low-lying basin. But the point is the distribution of those elevations. All but a small portion of the land on the map is shaded the palest, indicating the lowest topography and forming a broad, low plain. This is the ancient delta of the Amudarya. The rising ground (to 473m) occurs only on the southern and south-western margins of the map, likely to be the edges of the Karakum Desert or other upland geological formations. This landscape is not scenery alone; it is the primary controller of water flow and settlement possibility. The subtle southeast-to-northwest slope has shaped the course of the Amudarya and facilitated the gravity-fed flow of irrigation channels across the oasis. (Figure 1) The very lifeblood of Khorezm is absolutely the Amudarya river, which makes its way across the map from southeast to northwest, finally draining into the Aral Sea (not indicated to the north). Its course is the cardiovascular system of the region. The river's course is edged by a dense, dendritic pattern of canals, appearing as fine lines spreading out from the central channel, forming a web-like shape in the light-colored lowlands. It is evidence of centuries, if not millennia, of advanced hydraulic engineering for redistributing water from the river to the fields. The presence of the giant Tuyamuyin water reservoir (Tuyamuyin w.r.) in the eastern quadrant of the map 298 reflects a new extension of this ancient tradition. The extensive impoundment has a critical role to play in water storage and management, delivering a more reliable supply of water to irrigate and otherwise utilize within this arid terrain. The boundaries superimposed onto the DEM are highly informative. The "Oasis boundary" closely hugs the edge of the canal network and the areas of lowest elevation. It marks quite strongly the watered, fertile ground from the surrounding, likely arid, desert. This line traceable between life and desertion emphasizes the complete dependence of the region on man-managed water resources. Settlement patterns in Khorezm directly follow hydrology and topography. All of the major cities and towns fall within the periphery of the oasis, along the Amudarya or one of its main canals. Important urban centers such as Urgench, the modern-day administrative capital, and the ancient city of Konye-Urgench are situated near the river and its branches. The density of cities like Khonqa, Khiva, and Pitnak slightly further south also shows such dependence. The northwestern city of Nukus is also located within the irrigated area and acts as a local hub for the more downstream part of the delta. The lack of any major settlements whatsoever in the more elevated zones (the darker colored areas) ensures that without the river's water, land is not able to support large populations. Lastly, the provided DEM of the Khorezm region is not merely an elevation map; it is a story of people-environment interaction. It is the history of a civilization that has thrived for millennia in a parched plain by being adept at water management. The topography controlled the course of the river, the river made the canals possible, and the canals sustained the oasis, which supported the cities and molded the cultural landscape. The DEM at a glance presents the sensational contrast between the active, man-made ecosystem of the oasis and the barren desert it contains. This delicate equilibrium is now under threat from the risks of salination of land caused by intensive irrigation and from the current regional scarcity of water. The DEM is therefore a priceless tool not only for the historical geography of Khorezm but also for the essential environmental variables governing its sustainable future. In conclusion, the geospatial analysis of the Khorezm oasis DEM is a strong proof of the deterministic relationship between the region's flat terrain, life-sustaining Amudarya river, and millennia-long human adaptation. The elevation model confirms that the oasis is neither a happy circumstance but a direct result of the gentle slope of the ancient delta, making possible the development of a vast network of gravity-fed irrigation canals. This hydraulic network has been the sole factor in the transformation of a dry plain into fertile, densely populated agricultural center. The juxtaposition of the fertile, human-amended oasis with the barren desert 299 surroundings, evident in the DEM, emphasizes this extreme dependence. But this long-standing healthy system is now endangered by dangerous contemporary processes, initially from salinization of soils and local water scarcity. Therefore, this DEM and the applied approaches are not only retrospective tools but are a prerequisite for future sustainable management, providing the primary data for the solution of the current pressing environmental problems and for the provision of future sustainability of the Khorezm oasis. References: 1. 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