underfull \hbox (badness10000) in align environment

Question

I am facing a warning about the \hbox, and I noticed that I have a lot of space left between text and align environment. I would like to know how to reduce these gaps, to gain more spaces. You will find down below, the code of my home work

\documentclass[11pt,a4paper]{report}
\usepackage{graphicx}
\usepackage{amsmath}


 \usepackage{amssymb}
    \usepackage{amsmath}
\usepackage{amssymb}
\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\usepackage[export]{adjustbox} 
\usepackage{changepage} 

\begin{document}
\begin{adjustwidth}{-1cm}{-1cm}
\leavevmode
\rlap{\includegraphics[width=3cm, valign=t]{../Pictures/Capture.PNG} }
\hfill
\begin{minipage}[t]{\dimexpr\textwidth}
\centering
\makebox[4pt]{\Large\textbf{\emph{Ministère d'Enseignement Supérieur et la Recherche}}
}\\
\makebox[4pt]{\Large\textbf{\emph{Scientifique}}}\\
\medskip
\makebox[1pt]{\Large\textsc{Ecole National Supérieur des Travaux Publics}}\\
\makebox[0pt]{2019/2020}\\
\end{minipage}
\end{adjustwidth}
\begin{center}
Département :  DMS \\
Groupe : 02\\
Module: \textit{Hydraulique Appliqué}\\
GASMI Mohamed Wassim \\

\huge{\textbf{Devoir Maison 1}}\\
 \rule{\textwidth}{2pt}
\end{center}
\section*{Exercice 1}
\subsection*{1 - Calcule d'intensité dans chaque période de retour}
\subsubsection*{Pour T = 50 ans} 
\begin{align*}
P(i<I_{50})&= T - \frac{T}{50}\\
&= 0.98 = F\\
\end{align*}
- La variable réduite\\
\begin{align*}
U_{50} &= -ln(-lnF)\\
&=3.90
\end{align*}
\subsubsection*{Pour T= 100 ans}
\begin{align*}
P(i<I_{100})&= T - \frac{T}{100}\\
&= 0.99 = F\\
\end{align*}
- La variable réduite\\
\begin{align*}
U_{100} &= -ln(-lnF)\\
&=4.60
\end{align*}
\begin{center}
\begin{tabular}{|c|c|c|c|c|}
\hline 
Durée & Moyenne  & écart type & i50 & i100 \\ 
\hline 
6 & 121.1 & 27.79 & 193.10 & 228.09 \\ 
\hline 
15 & 92.10 & 27.88 & 188.28 & 207.80 \\ 
\hline 
30 & 73.50 & 28.63 & 183.82 & 203.86 \\ 
\hline 
45 & 58 & 23.23 & 138.14 & 154.40 \\ 
\hline 
60 & 50.8 & 23.94 & 133.39 & 150.14 \\ 
\hline 
\end{tabular} 
\end{center}


\end{document}

Please if anyone knows how to solve the problem, let know.

I look forward to hearing from you soon.

Thank you in advance.