Wyniki wyszukiwania - BazTech

1

SMAP products for prediction of surface soil moisture by ELM network model and agricultural drought index

Karamvand Aliakbar, Hosseini Seyed Abbas, Sharafati Ahmad

Acta Geophysica

|

2023

|

Vol. 71, no. 4

1845--1856

EN

In recent decades, the earth’s surface data have been collected more efficiently using remote sensing, which needs drought indexes update. In this study, soil moisture (SM) data were collected from the surface layer of a high humidity climate in northern Iran using Soil Moisture Active Passive (SMAP) and field measurement. After analyzing the data, we found that the average RMSE between the field and SMAP measurement was 0.054 m³/m³. Considering the same agricultural land use and the strong correlation of 0.92 between them, the validated SMAP data were used to propose an agricultural drought index. After data validation, the extreme learning machine (ELM) model was put to the test using sigmoid, triangular, sine, and hard-limit activation functions. Of all the activation functions tested, the model with the sigmoid activation function yielded the lowest amount of error and was therefore chosen. Five years of continuous daily SM as a target, five-year daily normalized difference vegetation index, land surface temperature, and precipitation were inputs to predict one-year daily SM time series in the humid climate. From 2021 to 2022, daily surface SM was predicted with the average RMSE=0.03 m³/m³ compared to the SMAP data. Finally, a new regional agricultural drought index based on 4 years of SMAP and 1-year prediction of SMAP from 2022 to 2023 was proposed. Further investigation is needed to conclude that the application of the presented index is reliable in other climates.

2

Comparative study of meteorological and hydrological drought characteristics in the Pekalen River basin, East Java, Indonesia

Harisuseno Donny

Journal of Water and Land Development

|

2020

|

no. 45

29--41

EN

Drought is known as a normal part of climate and including in a slow-onset natural hazard which may have several impacts on hydrology, agriculture, and socioeconomic. Drought monitoring, including its severity, spatial and duration is required and becomes an essential input for establishing drought risk management and mitigation plan. Many drought indices have been introduced and applied in regions with different climate characteristics in the last decades. This paper aims to compare standardized precipitation index (SPI) and rainfall anomaly index (RAI) along with standardized streamflow index (SSI) in Pekalen River Basin, East Java, Indonesia. The statistical association analyses, included the Pearson correlation (r), Kendal tau (τ), and Spearman rho (rs) were performed to examine the degree of consistency between monthly and annual drought index of SPI and RAI. Additionally, the comparative analysis was performed by overlapping both monthly and annual drought index from the SPI and RAI with the SSI at hydrological years. The study revealed that the characteristic of the annual drought index between the SPI and RAI exhibits pattern similarity which indicated by the high correlation coefficient between them. Further, the comparative analysis on each hydrological year showed that the SPI and RAI were very well correlated and exhibited a similar pattern with the SSI. Overall, the SPI shows better performance than the RAI for estimating drought characteristic either monthly or annual basis. Hence, the SPI is considered as a reliable and effective tool for analyzing drought characteristic in the study area.

3

Characterization of the climatic drought indices application to the Mellah catchment, North-East of Algeria

Bendjema Lina, Baba-Hamed Kamila, Bouanani Abderrazak

Journal of Water and Land Development

|

2019

|

no. 43

28--40

EN

Drought is one of the important phenomena resulting from variability and climate change. It has negative effects on all economic, agricultural and social sectors. The objective of this study is to rapidly detect climate dryness situations on an annual scale at the Mellah catchment (Northeast Algeria) for periods ranging from 31 years through the calculation of: the standardized precipitation index (SPI), the standardized Streamflow index (SSFI), the standardized temperature index (STI). Calculations made it possible to locate periods of drought more precisely by their intensity, duration and frequency, and detect years of breaks using the tests of Pettitt, rang, Lee and Heghinian, Hubert and Buishand. The use of the statistical tests for the rainfall series analyzed show all breaks, the majority of which are in 1996/1997 and 2001/2002. For the temperatures the breaks are situated in 1980/1981.

PL

Susza jest jednym z ważnych zjawisk wywoływanych zmianami klimatu. Wywiera ujemny wpływ na gospodarkę, rolnictwo i społeczeństwo. Celem przedstawionych badań było śledzenie sytuacji suszy klimatycznej w skali roku w zlewni Mellah (północnowschodnia Algieria) w ciągu 31 lat przez obliczenia: standaryzowanego wskaźnika opadu (SPI), standaryzowanego wskaźnika przepływu (SSFI) i standaryzowanego wskaźnika temperatury (STI). Obliczenia z zastosowaniem testów Petitta, rang, Lee i Heghiniana oraz Huberta i Buishanda umożliwiły dokładniejsze ustalenie okresów suszy przez analizę intensywności, czasu trwania i częstotliwości, umożliwiły też wykrycie lat przerw w ciągach suszy. Dzięki testom statystycznym dla serii analizowanych opadów wykazano okresy przerw, głównie w latach 1996/1997 i 2001/2002. Dane temperaturowe wskazywały na okresy przerw w latach 1980/1981.