Acquisition of Rainfall in Ungauged Basins: a Study of Rainfall Distribution Heterogeneity Based on a New Method

High-density precipitation data is always desired to capture the heterogeneity of precipitation to accurately describe the components of the hydrological cycle. However, equipping and maintaining a high-density rain gauge network involves high costs, and the existing rain gauges are often unable to meet the density requirements. The objective of this study is to provide a new method to analyze the spatiotemporal variability of the precipitation field and to solve the problem of insufficient site density. To this end, the Proper Orthogonal Decomposition (POD) method is proposed, which can analyze the spatial distribution characteristics of rainfall fields to solve data shortages. To demonstrate the feasibility and advantages of the proposed methodology, four districts and counties (Hongshan District, Jianli County, Sui County, and Xuanen County) in Hubei province in China were selected as case studies. The principal results are as follows. (1) The proposed method is effective in analyzing the spatiotemporal variability of the rainfall field to reconstruct rainfall data in ungauged basins. (2) Compared with the commonly used Thiessen Polygon method, the Inverse Distance Weighting method, and the Kriging method, POD is more accurate and convenient, and the root mean squared error is reduced from 3.22, 1.83, 2.19 to 2.09; the correlation coefficients are improved from 0.60, 0.85, 0.79 to 0.89, respectively. (3) The POD method performs particularly well in simulating the peak value and the peak time and can offer a meaningful reference for analyzing the spatial distribution of rainfall.

Characteristics of Landslide and Rainfall Areas in Majalengka Regency, West Java Province

Majalengka Regency is one of the districts with a high landslide hazard in West Java Province. They are mostly affected by heavy rainfall or prolonged rain. This study aims to classify landslide events in 2018-2019 based on physical factors consisting of slopes, soil types, lithology, land use, and vegetation density using the K-Means Clustering analysis method. To analyze the characteristics of rainfall that triggered landslides in 2018-2019 using the Thiessen polygon method. The results showed that the clustering of landslide events in 2018-2019 in Majalengka Regency was formed five clusters with the highest rainfall on the D-Day average in cluster 5, which is 49 mm/day. The highest average cumulative rainfall 3 days before the landslide events was in cluster 4, which is 80 mm/day. The highest average cumulative rainfall 5 days before the landslide events was in cluster 3 is 112 mm/day. The highest average cumulative rainfall 10 days before the landslide events was in cluster 1, which is 174 mm/day.

The Natural Disaster Prone Index Map Model in Indonesia Using the Thiessen Polygon Method

Natural Disasters are natural phenomena that occur at any moment that can cause loss. Indonesia is an archipelagic country located at the meeting of four tectonic plates and volcanic belts. This condition causes Indonesia to be prone to natural disasters. Therefore, it is necessary to make a natural disaster-prone index map model minimize the impact of natural disasters. In this research, the researchers used a Polygon Thiessen method for it was one of the mapping methods to determine a natural disaster based on Indonesia's vast surface and many disasters. The BNPB and Polygon Thiessen data comparison shows that BNPB data has a low level of vulnerability of 302, a moderate level of vulnerability of 148, and a high level of vulnerability of 58. In contrast, the Thiessen polygon has a low level of vulnerability of 297, a moderate vulnerability of 158, and a high vulnerability of 59. Comparing BNPB data and the Thiessen Polygon method found five differences from 40 data in the Papua region. Suggestions for further research to create an application-based information system so that it can be accessed in real-time.

Automating GIS input for distributed urban drainage modelling

The development of distributed urban drainage models is becoming more important as cities prepare for the challenges associated with climate change such as more intense precipitation events (McCarthy et al. 2010; Allan, 2011; Simõeset et al. 2011; Blumensaat et al. 2012; Leitãoet al. 2012). GIS-based tools were developed to generate input datasets for a 1-D distributed urban drainage model for part of Toronto's combined area, resulting in an efficient model development process compared to those utilizing manual approaches. These automatic GIS-based tools included the delineation of Wet Weather Flow (WWF) subcatchments (stormwater) and Dry Weather Flow (DWF) subcatchments (sanitary). It also included the determination of the intensity of rainfall on a more detailed scale than the coarse coverage provided by the City's rain gauges and the traditional Thiessen polygon interpolation method. Through testing the new tools designed in ModelBuilder, it was determined that 66% and 52% of DWF and WWF subcatchments respectively, were automatically delineated to a degree where they would be "Acceptable" for input into the urban drainage model, InfoWorks CS. Although the rainfall tools were able to continuously interpolate measured rainfall (on a seemingly unprecedented basis),and generate over 700 virtual rain gauges, the validity of the approach remains imperfect due to irresolvable inconsistencies between the City's gauges and those used for validation purposes.

Automating GIS input for distributed urban drainage modelling

The development of distributed urban drainage models is becoming more important as cities prepare for the challenges associated with climate change such as more intense precipitation events (McCarthy et al. 2010; Allan, 2011; Simõeset et al. 2011; Blumensaat et al. 2012; Leitãoet al. 2012). GIS-based tools were developed to generate input datasets for a 1-D distributed urban drainage model for part of Toronto's combined area, resulting in an efficient model development process compared to those utilizing manual approaches. These automatic GIS-based tools included the delineation of Wet Weather Flow (WWF) subcatchments (stormwater) and Dry Weather Flow (DWF) subcatchments (sanitary). It also included the determination of the intensity of rainfall on a more detailed scale than the coarse coverage provided by the City's rain gauges and the traditional Thiessen polygon interpolation method. Through testing the new tools designed in ModelBuilder, it was determined that 66% and 52% of DWF and WWF subcatchments respectively, were automatically delineated to a degree where they would be "Acceptable" for input into the urban drainage model, InfoWorks CS. Although the rainfall tools were able to continuously interpolate measured rainfall (on a seemingly unprecedented basis),and generate over 700 virtual rain gauges, the validity of the approach remains imperfect due to irresolvable inconsistencies between the City's gauges and those used for validation purposes.

Accessibility Analysis of Primary Healthcare Services in Mysore District Using Geospatial Techniques

The accessibility of healthcare centers is one of the most important indicators for measuring the efficiency of a healthcare system. Accessibility is a complex indicator that reflects the number of health care institutions, their geographical distribution and the impact of different types of barriers social, Economic and culture (1). Primary health centre which acts as the first level of contact between the population and health centers. It acts has a cornerstone of rural health services. Primary healthcare is affordable, accessible and appropriate care for the particular needs of a given population especially in rural areas. The main objectives of the study are to study the spatial distribution pattern and delineation of service area of primary health centers; to identify the gap between the availability and accessibility of health services. The base map of study area has been geo-referenced and digitized using ARC GIS software. The Global positioning system (GPS) was adopted to take the coordinate of all the existing primary health centers in the study area. Simple Euclidean buffers are mapped and analyzed to define the service area, Thiessen polygon and Nearest Neighbour Technique was used here to identify the availability of health services in Mysore district. The results reveal that, the spatial variation in the distribution of PHC’s, which were not evenly distributed across the study area and there is scarcity in the availability of workforce among the study area.

The Built Environment and the Development of Intermediate Socio-Spatial Units at Los Guachimontones, Jalisco, Mexico

Intermediate socio-spatial units (ISUs), materialized as neighborhoods and districts, were important elements in the ordering of the built environment in large ancient settlements. They are indicative of an increasing vertical and horizontal complexity because they lie between households and the governing authority. Collective action theory holds that ISUs can take many forms and can be created through bottom-up, top-down, or top-down/bottom-up processes. The distribution of ISUs in the context of other architectural elements illuminates the degree to which collective policies shaped urban landscapes. This article identifies districts and neighborhoods, two types of ISUs, at the site of Los Guachimontones (Jalisco, Mexico) through a study of its internal spatial organization. Intensive survey and mapping have identified thousands of architectural elements, including the circular complexes known as guachimontones. Thiessen polygon analysis reveals that guachimontones are an important feature of the site's spatial organization, as well as to the materialization of ISUs and other socio-spatial units. Broadly speaking, the organization of these built spaces reveals that their growth can be attributed to collectively oriented political strategies.

Database Development of Site Investigation Using GIS (A Case at Pulau Indah, Klang, Malaysia)

Site investigation works is very essential in every construction design work. Soil type and shear strength are the important parameter to design foundation system of insfrastructure project. Site investigations are not only costly, but also time consuming. There many geotechnical engineers tend to reduce site investigation works to decrease the construction cost. Based on these problems, the study was developed on site investigation database for Pulau Indah, Klang, Malaysia using Geographical Information System (GIS). Research study applied the Thiessen polygon method to obtain existing some informations type of soil and shear strength on this site. The research result was the database and map information. These data can be used for civil engineers to obtain site informations of soil type and shear strength parameter for future construction work related to the area.

ANALISIS NERACA AIR PADA SUB DAERAH ALIRAN SUNGAI CODE YOGYAKARTA

Water is one of the sources of human life. Population growth continues to increase and results in higher utilization of water sources. This will certainly affect the availability of water in the city of Yogyakarta. Water balance is a comparison between the water availability potential and the water demand of a place in a certain period. Water balance analysis is useful for knowing the amount of excess water (surplus) or lack of water (deficit) so that water use can be managed as well as possible. The calculation was done by analyzing the 10-year rainfall data using the Thiessen Polygon method to obtain the mean rainfall value. The available debit was calculated using the F.J. Mock method. The dependable discharge was calculated with 80% reliability from the 10-year debit data. The debit data was sorted from the largest to the smallest value, so that a probability value of 80% was obtained from the interpolation of the data sequence. Water demand was calculated based on the irrigation planning standard (KP-01). The results of the study show that the average water availability in the sub-watershed of Code River Yogyakarta was 527.92lt/sec. Based on the results of the analysis, the highest water deficit occurred in the first October at 278.40 l/sec and the lowest deficit was in the second July at 73.01 l/sec. However, the availability of water in certain months was quite abundant. Therefore, it is necessary to do a special study so that water is not wasted and can be used to cover water shortages in dry months. Keywords: Water balance, Water availability, Water demand, Code river, Thiessen polygon, FJ mock

Areal Precipitation Estimation Using Satellite Derived Rainfall Data over an Irrigation Area

The average precipitation on the irrigation field can be estimated from the Meteorology Observation Stations by using spatial interpolation methods such as Thiessen polygon and isohyetal curves. However, the fact that precipitation doesn't occur homogenous in spatial scales, spatial interpolation methodologies need a large number of meteorology stations for more accurate results. In recent years, remote sensing methods have diversified to estimate precipitation. In this study, performance of the satellite-based precipitation data was assessed to determine areal precipitation over an irrigation area. This study was conducted over left bank irrigation area located in the Çukurova Plain of Turkey. Relationship between CHIRPS satellite based on monthly precipitation data and 4 meteorology stations’ data were analyzed. Determination coefficients (R2) of the stations were found between 0.64 and 0.77, for point based comparison, R2 was calculated as 0.84 with Thiessen polygon method. It is concluded that the precipitation amount in the irrigated area can be estimated as accurately as classical methods such as Thiessen polygon with satellite-based precipitation data.