Free Global DEMs and Flood Modelling—A Comparison Analysis for the January 2015 Flooding Event in Mocuba City (Mozambique)

Flood hazard and risk analysis in developing countries is a difficult task due to the absence or scarce availability of flow data and digital elevation models (DEMs) with the necessary quality. Up to eight DEMs (ALOS Palsar, Aster GDEM, Bare Earth DEM, SRTM DEM, Merit DEM, TanDEM-X DEM, NASA DEM, and Copernicus DEM) of different data acquisition, spatial resolution, and data processing were used to reconstruct the January 2015 flood event. The systematic flow rate record from the Mocuba city gauge station as well as international aid organisms and field data were used to define both the return period peak flows in years for different flood frequencies (Tyear) and the January 2015 flooding event peak flow. Both visual and statistical analysis of flow depth values at control point locations give us a measure of the different hydraulic modelling performance. The results related to the Copernicus DEM, both in visual and statistical approach, show a clear improvement over the results of the other free global DEMs. Under the assumption that Copernicus DEM provides the best results, a flood hazard analysis was carried out, its results being in agreement with previous data of the effects of the January 2015 flooding event in the Mocuba District. All these results highlight the step forward that Copernicus DEM represents for flood hazard analysis in developing countries, along with the use of so-called “citizen science” in the form of flooding evidence field data acquisition.

Geospatial Technology Based Water Management Action Plan for South Forest Division of Nilgiris, Tamil Nadu

Aims: Recent climate change impacts rainfall patterns, increasing wildlife and livestock populations in higher densities, which are likely to aggravate water scarcity in forest areas. A sustainable water management strategy and action plan based on scientific inputs are crucial and need of the hour to resolve the water scarcity problem. Hence, the study aims to prepare an action plan and water management strategy for rangelands of Nilgiris using geospatial tools. Study Design: Field survey was conducted to identify the existing water storage structures and water requirement and ASTER GDEM and GIS were used to prepare the water management strategies for Nilgiris south forest division. Place and Duration of the Study: The study was carried out in Nilgiris south division located in between 760 28' 08’’and 760 44' 08" East longitude and 110 10' 81’’and 110 31' 80" North latitude during 2014-2016. Methodology: The study area has been delineated as macro watersheds, and the altitude, slope, forest cover and drainage lines were extracted from ASTER GDEM for generation thematic maps. Rainfall data for twenty years (1995-2014) was collected and runoff was worked out using runoff coefficient of a different land. A field survey was conducted for identifying the existing water storage structures, spatial occupancy of herbivores, spread and water requirement of invasive species in the Nilgiris south forest division. Results: GIS based thematic maps for slope, contour, area coverage under forest range and macro watershed have been prepared, and water availability and water balance components like runoff and evapotranspiration have been determined. After identifying water availability and water balance according to the site conditions and strategies one Earthen cum masonry embankment, 2 Earthen pond with Major check dam, 2 Masonry embankments, 2 Major check dam 7 Medium check dam 100 Minor check dam, 1 RCC Embankment and 99 gabion check dams in South forest division of Nilgiris. Conclusion: Suitable locations were identified and location specific water harvesting structures have been suggested to store 68844 cum of water.

Exploratory Three Dimensional Cartographic Visualisation of Geolocated Datasets

<p>While digital technologies have vastly facilitated the generation and consumption of cartographic visualisations, the majority still conform to traditional two-dimensional map making guidelines. Consequently, design principles for three-dimensional cartographic models are still in their infancy and require further exploratory research to establish a comprehensive design framework. The free availability of high resolution global digital elevation models (GDEM), such as the ASTER GDEM (NASA LP DAAC, METI, 2011), makes it possible to develop accurate three-dimensional landscape visualisations and offer more intuitive and immersive representation of spatial information. Combined with the prevalence of geolocated content in both online data-repository and social-media platforms, there exists a wealth of material to be mined, interpreted and juxtaposed in exploratory cartographic visualisations. This thesis aims to establish a flexible and iterative procedural workflow to acquire, interpret and visualise 3D geolocated datasets, without compromising aesthetic control. Synergic with the procedural approach required for data collection and analysis, a procedural approach is used in the design of the visual output. This workflow aims to maximise automation and allow for the interpretation of a range of different data sources. The creative output of this process explores emergent cartographic principles for optimal three-dimensional spatial visualisation and investigate data presentation techniques beyond traditional two-dimensional geo-visualisation guidelines. Informed by exploratory literature review and research through design theories, this practice-led thesis documents the iterative prototyping leading to the creation of a set of map-based infographics showcasing effective application of cartographic and data visualisation principles in a 3D geospatial context. These design prototypes and critical report of workflow refinement hope to contribute to the development of three-dimensional geographic modelling conventions.</p>

Exploratory Three Dimensional Cartographic Visualisation of Geolocated Datasets

<p>While digital technologies have vastly facilitated the generation and consumption of cartographic visualisations, the majority still conform to traditional two-dimensional map making guidelines. Consequently, design principles for three-dimensional cartographic models are still in their infancy and require further exploratory research to establish a comprehensive design framework. The free availability of high resolution global digital elevation models (GDEM), such as the ASTER GDEM (NASA LP DAAC, METI, 2011), makes it possible to develop accurate three-dimensional landscape visualisations and offer more intuitive and immersive representation of spatial information. Combined with the prevalence of geolocated content in both online data-repository and social-media platforms, there exists a wealth of material to be mined, interpreted and juxtaposed in exploratory cartographic visualisations. This thesis aims to establish a flexible and iterative procedural workflow to acquire, interpret and visualise 3D geolocated datasets, without compromising aesthetic control. Synergic with the procedural approach required for data collection and analysis, a procedural approach is used in the design of the visual output. This workflow aims to maximise automation and allow for the interpretation of a range of different data sources. The creative output of this process explores emergent cartographic principles for optimal three-dimensional spatial visualisation and investigate data presentation techniques beyond traditional two-dimensional geo-visualisation guidelines. Informed by exploratory literature review and research through design theories, this practice-led thesis documents the iterative prototyping leading to the creation of a set of map-based infographics showcasing effective application of cartographic and data visualisation principles in a 3D geospatial context. These design prototypes and critical report of workflow refinement hope to contribute to the development of three-dimensional geographic modelling conventions.</p>

ANALISIS MORFOLOGI FISIK KALDERA MASURAI JAMBI MENGGUNAKAN CITRA SATELIT RESOLUSI TINGGI

Kaldera Masurai Jambi merupakan kaldera terakhir yang ditemukan di Pulau Sumatera. Keberadaan kaldera yang berumur Plistosen Akhir ini sebagai bagian dari pembentukan kaldera di sepanjang Perbukitan Barisan. Informasi geologi terkait kaldera ini sangat sedikit, sehingga diperlukan penelitian geologi detail yang diawali dengan analisis morfologi fisik kaldera. Tujuan penelitian ini untuk memahami morfologi fisik Kaldera Masurai dengan menggunakan analisis citra resolusi tinggi yang merupakan upaya untuk mengetahui proses pembentukan morfologi kaldera dan posisinya secara geologi terhadap keberadaan kaldera lainnya. Untuk mendukung penelitian ini, menggunakan metode pengamatan dan analisis model elevasi digital ASTER-GDEM, Citra Satelit Ikonos dan Citra Quickbird, observasi bentang alam, dan pemetaan geologi. Morfologi fisik Kaldera Masurai terdiri dari Morfologi puncak kaldera dengan bentang alam dan manifestasi seperti cincin kaldera, kawah gunung api dari Kawah Kumbang, Kawah Mabuk, Kawah Merah Tanjung Brugo, dan fosil Kawah Dikit, dan Gunung Masurai Muda. Morfologi lereng kaldera proksimal-medial dengan bentang alam dan manifestasi meliputi kerucut Gunung Dikit yang merupakan bagian dari kerucut parasiter Gunung Masurai Tua dan kerucut Gunung Lupi yang merupakan bagian dari kerucut parasiter Gunung Masurai Muda. Morfologi kaki atau distal kaldera dengan bentang alam dan manifestasi seperti Danau Pauh dan Danau Kecil sebagai bagian dari jejak erupsi samping atau kerucut sinder Gunung Masurai Muda. Karakteristik bentang alam dan manifestasi kaldera merupakan hasil proses geologi yang membentuk morfologi Kaldera Masurai.

Impacts of Land Cover and Greenness Change on Soil Loss and Erosion Risk in Damota Area Districts, Southern Ethiopia

Soil erosion is a key problem in Ethiopia in view of tropical climate, lack of vegetation, and landscape relief. Therefore, soil and water conservation (SWC) measures have been practiced, but their impacts on soil loss have not been estimated adequately. The RUSLE modeling was applied using satellite imageries, ASTER GDEM, rainfall, and soil data to estimate total annual soil loss for a 100 km2 hilly and highly populated area in Ethiopia. Soil loss decreased in the Damota districts from 21 to 13 million tons from 2000 to 2020. Similarly, the average annual soil loss decreased by 36%. Very slight-risk areas (< 5 t ha−1 yr−1) increased from 42.66 to 53.72%, and very high-risk areas (> 50 t ha−1 yr−1) decreased from 12 to 5%. Soil and water conservation measures showed an important implication against soil erosion through improved land cover and landscape greenness. However, still, the rate of soil erosion is high compared to the soil loss tolerance of 1–6 t ha−1 yr−1 for the Ethiopian highlands.

ANALISIS PENGINDERAAN JAUH DAN PEMODELAN 3D FAULT FRACTURE DENSITY (FFD) DALAM PENENTUAN ZONA PERMEABILITAS PERMUKAAN DI WILAYAH PANAS BUMI GUNUNG TAMPOMAS, JAWA BARAT

Wilayah Gunung Tampomas yang terletak di Kecamatan Buahdua, Kecamatan Conggeang, dan Kecamatan Tanjungkerta, Kabupaten Sumedang, Jawa Barat dipilih sebagai daerah penelitian karena diperkirakan memiliki potensi panas bumi dengan hadirnya manifestasi panas bumi berupa mata air panas di sekitarnya. Kemunculan manifestasi berhubungan dengan zona permeabilitas yang dikontrol oleh struktur geologi. Kelurusan punggungan dan lembah diamati dan dianalisis menggunakan citra penginderaan jauh ASTER GDEM dan peta Rupa Bumi Indonesia (RBI), skala 1:25.000. Tujuan penelitian untuk mengetahui hubungan antara permeabilitas dengan kemunculan manifestasi panas bumi di daerah penelitian. Metode penelitian dengan melakukan analisis penginderaan jauh dan Fault Fracture Density (FFD) menggunakan pemodelan 3D micromine software. Hasil analisis penginderaan jauh dengan azimut penyinaran dari 0˚, 45˚, 90˚, 135˚ dan altitude 45˚ memperlihatkan pola utama kelurusan punggungan–lembah yang diinterpretasikan sebagai patahan memiliki arah relatif barat laut-tenggara dan timur laut-barat daya. Indikasi struktur geologi di lapangan diperlihatkan oleh morfologi bentuk punggungan lembah, di beberapa tempat memiliki tebing curam membentuk gawir sesar dan faset segitiga. Hasil analisis FFD di daerah penelitian memiliki tingkat permeabilitas yang bervariasi dengan nilai FFD rendah (0,00–3,00 km-1), sedang (3,00-6,00 km-1) dan tinggi (6,00–9,33 km-1). Manifestasi panas bumi muncul pada zona permeabilitas yang memiliki nilai FFD sedang hingga tinggi yang ditandai oleh warna jingga dan merah. Dari pemodelan 3D micromine software terhadap zona permeabilitas dan ploting mata air panas di permukaan terlihat secara jelas kemunculan mata air panas ke permukaan difasilitasi oleh patahan yang berkembang di daerah penelitian.

ANALIZA TAČNOSTI ASTER GDEM v3 DIGITALNOG MODELA TERENA

U radu je prikazana detaljna analiza parametara koji definišu kvalitet kreiranog GDEM-a. Nakon opsežne analize dobijenih rezultata, prikazani su i algoritmi kojima se mogu poboljšati vrednosti dobijenih parametara ASTER GDEM-a v3 kojima se definiše tačnost ovog globalnog modela.