Watershed Ecology and the Environment最新文献

In highly modified and managed systems the balance of freshwater inputs discharged to estuarine systems are important to maintain salinity balances and thus estuarine function. However, the availability of freshwater is highly dependent on upstream water management to provide flood protection whilst meeting freshwater demand for people and the environment. In South Florida, water is managed by a water control plan with Lake Okeechobee at the center. Currently, water levels within the lake are managed based on the Lake Okeechobee Regulation Schedule of 2008. The new regulation schedule, Lake Okeechobee System Operating Manual (LOSOM), updates water management rules while attempting to balance the needs of downstream systems; salinity and water quality in the Caloosahatchee and Saint Lucie (northern) estuaries; and more water for the southern Everglades. This study evaluates LOSOM relative to ecologically significant performance measures for the northern estuaries. Overall, the proposed regulation schedule is expected to provide a more sustainable flow regime to the estuaries by reducing stressful and damaging discharge events. Moreover, new management rules combined with new infrastructure are expected to reduce low discharge events to the Caloosahatchee estuary and reduce stress on key indicator species such as Vallisneria americana during the wet season. This regulation schedule provides improved conditions for the estuaries at the expense of higher Lake Okeechobee stages. Future restoration and water management will maintain the benefits afforded to the estuaries while at the same time reducing the impacts to Lake Okeechobee resulting in a more sustainable and resilient system.

The impact of an earthquake on river water quality is massive, and the quality of life and environment typically changes as a result of a quick drop in the environment system. A 6.0 magnitude earthquake struck the Ranau area of Sabah, Malaysia, in 2015, affecting the Liwagu River’s water quality. Satellite data on earthquakes, coupled with local water quality data collecting, allows for an accurate assessment of water quality parameters. As a result, the Sabah Water Department provided secondary water quality data from Bambangan and Kimolohing on the Liwagu River. Following that, turbidity, color, pH, electric conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), nitrate (NO₃⁻), iron (Fe), manganese (Mn), aluminum (Al), alkalinity, hardness, chloride (Cl-), and sulfate (SO₄²⁻) were chosen. The investigation discovered unusually high turbidity and color in the water on June 17, 2015, as well as elevated levels of Al, Fe, and Mn. DO concentrations plummeted to 3.8 mg/L on the same day. Statistical analyses, employing the Kruskal-Wallis test, identified significant parameters—Fe (0.001) and Mn (0.001) at both stations, turbidity (0.001), and color (0.003) in Kimolohing, and Al (0.027) in Bambangan. Recovery in water quality took two weeks to two months, with iron and manganese requiring over six months for restoration. The earthquake didn’t solely dominate the impact but altered pollution sources to the river. The discussion highlights the synthesis of spatial and temporal dynamics enabled by the integration of ground and satellite data. This approach not only refines retrospective analyses but also propels us into predictive modeling, enhancing preparedness for future seismic events. The study’s holistic environmental impact assessment extends beyond water quality, unraveling cascading effects on ecosystems, soil, and vegetation. Informed decision-making for sustainable resource utilization emerges as a pivotal outcome, emphasizing the interconnectedness of seismic activity, rainfall patterns, and water quality. The study serves as a blueprint for future environmental assessments, emphasizing multifaceted approaches to understand and mitigate the complex impacts of seismic events on water resources.

Although numerical water quality models offer valuable insights into thermal stratification (TSn) and mixing dynamics in lakes, they are often resource and time consuming, limiting their applications for investigating a large number of lakes over a wide geographical area. An alternative approach is using well-known thermal classification systems, which require minimum data to provide acceptable information on TSn and mixing patterns in lakes. This study investigates the TSn and mixing regimes in 198 dam reservoirs located in Iran, using Lewis’s method for analysis. The results highlight that all 198 investigated reservoirs in Iran can be represented by six out of eight possible thermal classifications. The majority of the northeastern reservoirs are categorized as “warm monomictic”. For the reservoirs located in the north and northwest regions, all six thermal classes are observed. However, in the southern part of Iran, only the reservoirs of “continuous warm polymictic”, “warm monomictic”, and “discontinuous cold polymictic” types are located. Our findings reveal that 35.4%, 21.2%, 17.2%, 13.1%, 6.6%, and 5.6% of the investigated reservoirs were classified as “warm monomictic”, “discontinuous cold polymictic”, “continuous cold polymictic”, “dimictic”, “discontinuous warm polymictic”, and “continuous warm polymictic”, respectively. Our results can provide authorities with initial insights for further in-depth studies and decision-making into water quality management in Iran and enhancement strategies for the reservoirs in the country.

Flash flood causes severe damage to the environment and human life across the world, no exception is Bangladesh. Severe flash floods affect the northeastern portion of Bangladesh in the early monsoon and pose a serious threat to every aspect of socioeconomic development and environmental sustainability. To manage the threat and reduce flood loss, the map of flash flood susceptible zones plays a key role. Thus, the aim of this research is to map the flash flood-susceptible areas of the northeastern haor areas of Bangladesh utilizing GIS-based bivariate statistical models. The models utilized are frequency ratio (FR), weights of evidence (WoE), certainty factor (CF), Shanon’s entropy (SE) and information value (IV). Among the 250 identified flash flood locations, 80 % data was used for training purposes and 20 % data for testing purposes. Eleven selected conditioning factors of flash flood include elevation, slope, aspect, curvature, TWI, TRI, SPI, distance to stream, stream density, rainfall and physiography. The calculated weights are assigned to the conditioning factors using ArcGIS environment to prepare the final flash flood maps. Results of AUC of ROC indicate WoE (success rate = 0.833 and prediction rate = 0.925) is the best model for flash flood susceptibility mapping followed by FR (success rate = 0.828 and prediction rate = 0.928) and SE (success rate = 0.827 and prediction rate = 0.923). According to the models, topographic (flat area) and hydrologic factors significantly control flash flood occurrence in the study area. The prepared flash flood susceptibility maps will be helpful for disaster managers and haor master planners of the study area.

The expansion of saline-alkali paddy fields, coupled with the application of large amounts of nitrogen (N) fertilizers, has given rise to a host of environmental concerns. While N and carbon (C) are vital indicators for assessing soil fertility, their dynamic characteristics in saline-alkali paddy soil remain obscure. To address this knowledge gap, we established paddy mesocosms with five distinct N-fertilizer treatments: control without N-fertilizer (CK), urea (U), urea with inhibitors (UI), organic–inorganic compound fertilizer (OCF) and C-based slow-release fertilizer (CSF). The objective was to monitor the dynamic changes of various N and soil organic-C (SOC) during a 137-day rice growing season, and to clarify the microbiological characteristics. By the end of the rice growing season, soil ammonia-N (NH₄⁺-N) concentrations were UI > OCF > CSF > U > CK, and UI had a significant difference (p < 0.05) with all the other four treatments. Soil nitrate-N (NO₃⁻-N) concentrations in OCF and CSF treatments were 5.64 ± 1.25 mg kg⁻¹ and 6.81 ± 0.29 mg kg⁻¹, respectively, significantly (p < 0.05) higher than U and UI treatments. NH₄⁺-N showed a negative correlation with NO₃⁻-N regardless of the N-fertilizer types, and a significant (p < 0.01) positive relationship with alkali-hydrolyzable N (AHN). A significant (p < 0.01) positive relationship existed between total-N (TN) and Bacteria 16S rRNA gene. The SOC had a significant (p < 0.05) positive relationship with mcrA gene. During the entire rice growing season, CSF treatment had lower mean TN and SOC concentrations than all the other treatments, and exhibited the highest TN and total organic-C (TOC) content in rice. In summary, the UI can increase the residual NH₄⁺-N in saline-alkali paddy fields, and the CSF is a better choice for growing rice.

The invasive species Spartina alterniflora has significantly disrupted the ecological stability of coastal wetland ecosystems. Consequently, its control has become an important aspect of coastal wetland conservation. When controlling S. alterniflora, it is imperative to assess the ecological impacts of control methods. In this study, the effects of different control methods, i.e. “mowing + flooding” (MF) and “mowing + plowing” (MP), on the soil carbon and nitrogen contents in coastal wetlands were investigated in the Yellow River Delta, China. The results showed that the contents of soil organic carbon, inorganic carbon, and total nitrogen in the MF area within 2 years after treatment were 2.03–3.93 g/kg, 13.74–16.06 g/kg, and 0.24–0.47 g/kg, respectively, which were 36.33 %–-199 %, 2.91 %–36.71 % and 115.42 %–212.09 % higher than that those in the CK area, respectively. The C/N ratio in the MF treatment was 6.98–8.54, which was 5.42 %–40.30 % lower than that in the CK treatment. The contents of soil organic carbon, inorganic carbon, and total nitrogen in the MP area were 1.52–2.3 g/kg, 13.07–14.94 g/kg, and 0.2–0.32 g/kg, respectively, which were 15.91 %–54.18 %, 0.97 %–15.56 % and 35.19 %–182.26 % higher than those in the CK area. The C/N ratio in the MP area was 14.72 %–46.79 % lower than that in the CK area. Correlation analysis revealed that the soil carbon and nitrogen contents in the MF area were significantly positively correlated with the soil water content and electrical conductivity, and the C/N ratio was significantly negatively correlated with the soil sand content. In the MP area, the soil carbon and nitrogen contents were affected by the soil water content and electrical conductivity. The soil organic carbon content was also significantly negatively correlated with soil pH and significantly positively correlated with soil clay content. The C/N ratio was significantly negatively correlated with the total nitrogen content. Overall, the effects of MF on the soil carbon and nitrogen content in coastal wetlands were greater than those of MP. Future studies need to pay attention to the changes in tidal hydrological processes to more accurately assess the impacts of the control of S. alterniflora on the overall carbon sink capacity of the intertidal zone.