Water Stage Research Articles

Varied hydrological regime of a semi-arid coastal wetland

Abstract Coastal wetlands are transitional ecosystems between land and sea. Participants of citizen science programs have detected frequent floods in wetlands, as well as small pools that appear and then disappear. Considering that it is not clear whether their main hydrologic drivers are of marine or continental origin, we studied the El Culebrón wetland located in the Chilean semi-arid zone. El Culebrón is strongly influenced by extreme rain events. This wetland also experiences seasonal changes in its water stage (WS). A high mean sea level agreed with 41% of the WS rises. High intensity storm surges coincided with 53% of WS peaks. A small tsunami in 2022 impacted the WS, and another very intense tsunami flooded it in 2015. An apparent diurnal cycle in the WS was discarded due to an instrumental artifact. The combination of the aforementioned factors provided an explanation for 91% of the WS rises. The probable and novel mechanism for sea level and storm surge influence on WS is the formation of a sand barrier between the coastal lagoon and the sea. As a whole, El Culebrón receives varied influences from both the sea and the mainland, but it seems to be more dependent on freshwater sources.

SOLUTIONS PROPOSED FOR THE NAVIGATION PROBLEM DOWNSTREAM ZEFTA BARRAGES

The Nile navigable Damietta branch extends between Cairo and Damietta open seaport on the Mediterranean. For safe navigation throughout the branch, a 2.30 m minimum flow depth (MFD) is required. A recovery project to improve the branch navigation was started in 1999 and completed in 2005. The project was to implement a 40 m wide navigable waterway. About 6.50 million m3 of bed materials had been removed from bottlenecks at $ 18.20 million cost. In 2003, the construction of a new lock of 150.0 m length, 17.0 m width and (1.50) m bed level was completed on Zefta Barrages (ZB) east side to meet the navigation requirements. The barrages are located at Km 119.625 downstream (D/S) El-Roda Gauge in Cairo. However, the resulting water stage (WS) D/S (ZB) during low discharges was insufficient to provide the MFD. Field studies were conducted to reveal the reasons. They found the branch flow carrying capacity had increased due to excessive dredging which caused a decline in WSs D/S (ZB). Analyzing the hydrologic and topographic conditions, two solution concepts were reached; either to raise the WS by 0.70 m or to lower the bed level of the diversion channel located D/S the new lock by 1.0 m. Therefore, this study aims to introduce solutions to overcome the problem. The solutions are to use a D/S rubber weir for raising the WS or construct a new lock within the D/S diversion channel for lowering the bed level or build new barrages with a new lock.

Assessment of the allelopathic potential of 17 Iranian barley cultivars in different development stages and their variations over 60 years of selection

Laboratory experiments were conducted to determine the allelopathic potential of 17 Iranian barley cultivars in four development stages and their variations over the last 60 years of collection. Imbibed seeds and water leachates that were extracted from the barley plants at the seedling, tillering, stem elongation, and heading stages were used for the bioassays, including filter paper, neighboring barley seeds in soil, and soil mixed with dried barley residues. The experiments were conducted with the use of wild mustard (Sinapis arvensis) as the test plant. The Germination Rate Index (GRI) and emergence of S. arvensis were inhibited on both the filter paper and soil. The highest inhibitory effect was seen with the tillering stage's water leachate on filter paper. The GRI decreased in response to the increased density of barley imbibed seeds. The germination was less affected by the presence of barley seeds from the soil than those from the filter paper. The GRI of S. arvensis seeds was lower in the older than in the recently developed cultivars. Although there were some fluctuations in the GRI value with time, the germination inhibitory effect has decreased as new, higher‐yielding cultivars have been released.

ライフスタイル概念に基づく水利用構造分析に関する考察

The aging and the social advance of womenmove ahead and also the material abundance makes choice of the way of the life various ones. Of course, it thinks that the trend brings a changeof water use structure in the household. Above-mentioned viewpoint is important when thinking of the plan of disaster mitigation against earthquake and drought. It becomes necessary to evaluate the water use structure in the household itself from the viewpoint of dealing with the old society and disaster mitigation.This paper proposes one approach which applied a life style concept to this problem. First, we explain a life style concept and a water use structure model in a household. The model consist of basic attribute of household, apparatus, water use act and consciousness. We analyze about these items in case study and show that each life stage's water use structures are different. Furthermore we consider the water use act in case of disaster from two viewpoints of the life line dependence type and the commercial function dependence type which defined by life style factors and finally we show the effectiveness of the life style approach.