This thesis addresses a number of problems in the field of Active Wave Absorption Systems (AWAS) in wave flumes. The main objective is to establish new tools and methodologies for the improvement of existing AWAS that play a key role in Costal Engineering studies. The main problems addressed are: i) estimation of uncertainties in wave gauges measurements, ii) separation of incident and reflected waves, and iii) new methods for correcting the wave generator paddle movement in order to achieve simultaneous generation and absorption. For the first problem, a method to determine the uncertainties associated to amplitude and frequency estimation based on wave gauge measurements is proposed. Additionally, a sensitivity analysis of active absorption systems with respect to wave parameters consisting of amplitude, frequency, and phase is conducted. In general, the methods for separation of incident and reflected waves described in the literature do not address the robustness to noise measurements explicitly. Moreover, the singularity problems that arise in the separation process, related to the spacing between wave gauges, may lead to noise amplification and numerical instabilities. The situation is further aggravated by the fact that the only real-time separation method applied to AWAS found in the literature is limited to two gauges and is sensitive to noise. With a view to overcoming these limitations, a new method for the separation of incident and reflected waves based on linear theory of irregular waves, that is robust to noise measurements and can be implemented using an arbitrary number of gauges, is proposed. The problem of numerical instabilities associated with singularities is eliminated. The method is applicable in real-time directly to gauges measurement signals with no need to resort to pre-filtering stage processes. Finally, an analysis of the effect of the instantaneous position of the wave generator paddle on wave re-reflection is carried out and an innovative methodology is proposed that introduces a feedback mechanism of the paddle position in the correction of the wave generator paddle movement to achieve simultaneous generation and absorption. This approach enables attenuation of the harmonic distortion and amplification of the reflected wave in the re-reflection problem, an important issue that so far has not been addressed in the literature.