Quantifying the impacts of dams on riverine hydrology under non-stationary conditions using incomplete data and Gaussian copula models

Statistical analysis of the k/n(G) system with dependent competing failure components influenced by Gumbel-Hougarrd Copula and progressively hybrid censored data

Consider a k / n ( G ) system, in which the system components are composed of multiple dependent failure mechanisms, and the dependence between the mechanisms is connected by the Gumbel-Hougarrd (GH) Copula. This paper presents a progressively hybrid censored test based on the k / n ( G ) system. Based on the censored test, the IFM(Marginal inference) method is used to estimate the model parameters and system reliability. Meanwhile, the MH (Metropolis-Hastings) sampling mixed with the Gibbs sampling method is proposed to realize the Bayes estimation of the model parameters and system reliability. Also, under the non-informative prior conditions, the conditional posterior density of the shape parameters of the marginal Weibull distribution is proved to be log-concave. The Monte Carlo simulation results showed that the proposed Bayes method is better than the traditional IFM method. Finally, the model and method proposed in this paper are applied to real data.

A baseline assessment of hydrologic alteration degree for the Mexican catchments at gauged rivers (2016)

River regime has been modified in several freshwater bodies around the world. This alteration has led to species loss, water pollution, higher or lesser economic profits, changes in magnitude, timing, duration and rate change of flow, among others. Thus, hydrologic alteration assessment allows evaluating the regime parameters so that stakeholders, decision-makers, and dams managers may take efficient actions to mitigate or rehabilitate riparian ecosystems. In the present study, Hydrologic Alteration Indexes on Rivers (IAHRIS, for its acronym in Spanish) and the Mexican standard approach were considered to evaluate 1150 gauged catchments in Mexico and come up with an alteration baseline for 67.03% of the country surface. The comparison may assist stakeholders to propose potential changes in the Mexican standard approach. Results reveal that 232 analyzed catchments can be considered as non-altered according to IAHRIS. In stark contrast, there are 281 non-altered catchments in Mexico in agreement with the official standard approach. Altered catchments are mainly impacted by minimum flow metrics and connectivity discharge. Additionally, the correlation between alteration indexes and 5 socio-economic variables was checked to identify which variables may greatly impact hydrologic alteration evolution or mitigation. From the five selected variables, the Human Development Index is significatively correlated to extreme minimum metrics (p = 0.94) while the Gross Domestic Product to extreme maximum metrics (p = 0.90).